| 1. |
- Ke, You, et al.
(författare)
-
Defect Passivation for Red Perovskite Light-Emitting Diodes with Improved Brightness and Stability
- 2019
-
Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 10:3, s. 380-385
-
Tidskriftsartikel (refereegranskat)abstract
- Efficient and stable red perovskite light-emitting diodes (PeLEDs) are important for realizing full-color display and lighting. Red PeLEDs can be achieved either by mixed-halide or low-dimensional perovskites. However, the device performance, especially the brightness, is still low owing to phase separation or poor charge transport issues. Here, we demonstrate red PeLEDs based on three-dimensional (3D) mixed-halide perovskites where the defects are passivated by using 5-aminovaleric acid. The red PeLEDs with an emission peak at 690 nm exhibit an external quantum efficiency of 8.7% and a luminance of 1408 cd m(-2). A maximum luminance of 8547 cd m(-2) can be further achieved as tuning the emission peak to 662 nm, representing the highest brightness of red PeLEDs. Moreover, those LEDs exhibit a half-life of up to 8 h under a high constant current density of 100 mA cm(-2), which is over 10 times improvement compared to literature results.
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| 2. |
- Miao, Yanfeng, et al.
(författare)
-
Stable and bright formamidinium-based perovskite light-emitting diodes with high energy conversion efficiency
- 2019
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Solution-processable perovskites show highly emissive and good charge transport, making them attractive for low-cost light-emitting diodes (LEDs) with high energy conversion efficiencies. Despite recent advances in device efficiency, the stability of perovskite LEDs is still a major obstacle. Here, we demonstrate stable and bright perovskite LEDs with high energy conversion efficiencies by optimizing formamidinium lead iodide films. Our LEDs show an energy conversion efficiency of 10.7%, and an external quantum efficiency of 14.2% without outcoupling enhancement through controlling the concentration of the precursor solutions. The device shows low efficiency droop, i.e. 8.3% energy conversion efficiency and 14.0% external quantum efficiency at a current density of 300 mA cm(-2), making the device more efficient than state-of-the-art organic and quantum-dot LEDs at high current densities. Furthermore, the half-lifetime of device with benzylamine treatment is 23.7 hr under a current density of 100 mA cm(-2), comparable to the lifetime of near-infrared organic LEDs.
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| 3. |
- Wang, Yuming, et al.
(författare)
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High-Efficiency Flexible Solar Cells Based on Organometal Halide Perovskites
- 2016
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 28:22, s. 4532-4540
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Tidskriftsartikel (refereegranskat)abstract
- Flexible and light-weight solar cells are important because they not only supply power to wearable and portable devices, but also reduce the transportation and installation cost of solar panels. High-efficiency organometal halide perovskite solar cells can be fabricated by a low-temperature solution process, and hence are promising for flexible-solar-cell applications. Here, the development of perovskite solar cells is briefly discussed, followed by the merits of organometal halide perovskites as promising candidates as high-efficiency, flexible, and light-weight photovoltaic materials. Afterward, recent developments of flexible solar cells based on perovskites are reviewed.
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| 4. |
- Wang, Yuming, et al.
(författare)
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Light-induced degradation of fullerenes in organic solar cells : a case study on TQ1:PC71BM
- 2018
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 6:25, s. 11884-11889
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Tidskriftsartikel (refereegranskat)abstract
- The stability of organic solar cells (OSCs) is critical for practical applications of this emerging technology. Unfortunately, in spite of intensive investigations, the degradation mechanisms in OSCs have not been clearly understood yet. In this report, we employ a range of spectroscopic and transport measurements, coupled with drift-diffusion modelling, to investigate the light-induced degradation mechanisms of fullerene-based OSCs. We find that trap states formed in the fullerene phase under illumination play a critical role in the degradation of the open-circuit voltage (V-OC) in OSCs. Our results indicate that the degradation is intrinsic to the fullerenes in OSCs and that alternative acceptor materials are desired for the development of stable OSCs.
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| 5. |
- Xu, Lei, et al.
(författare)
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The Role of Solution Aggregation Property toward High-Efficiency Non-Fullerene Organic Photovoltaic Cells
- 2024
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
-
Tidskriftsartikel (refereegranskat)abstract
- In organic photovoltaic cells, the solution-aggregation effect (SAE) is long considered a critical factor in achieving high power-conversion efficiencies for polymer donor (PD)/non-fullerene acceptor (NFA) blend systems. However, the underlying mechanism has yet to be fully understood. Herein, based on an extensive study of blends consisting of the representative 2D-benzodithiophene-based PDs and acceptor-donor-acceptor-type NFAs, it is demonstrated that SAE shows a strong correlation with the aggregation kinetics during solidification, and the aggregation competition between PD and NFA determines the phase separation of blend film and thus the photovoltaic performance. PDs with strong SAEs enable earlier aggregation evolutions than NFAs, resulting in well-known polymer-templated fibrillar network structures and superior PCEs. With the weakening of PDs' aggregation effects, NFAs, showing stronger tendencies to aggregate, tend to form oversized domains, leading to significantly reduced external quantum efficiencies and fill factors. These trends reveal the importance of matching SAE between PD and NFA. The aggregation abilities of various materials are further evaluated and the aggregation ability/photovoltaic parameter diagrams of 64 PD/NFA combinations are provided. This work proposes a guiding criteria and facile approach to match efficient PD/NFA systems. A systematic study of the representative organic photovoltaic systems shows that the aggregation competition between polymer donor (PD) and non-fullerene acceptor (NFA) is a decisive factor in the phase separation of blend film and thus the photovoltaic performance. Based on 64 PD/NFA combinations, the aggregation ability/photovoltaic parameter heatmaps are plotted, providing a new matching rule for developing high-efficiency PD/NFA systems. image
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| 6. |
- Yang, Rong, et al.
(författare)
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Inhomogeneous degradation in metal halide perovskites
- 2017
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 111:7
-
Tidskriftsartikel (refereegranskat)abstract
- Although the rapid development of organic-inorganic metal halide perovskite solar cells has led to certified power conversion efficiencies of above 20%, their poor stability remains a major challenge, preventing their practical commercialization. In this paper, we investigate the intrinsic origin of the poor stability in perovskite solar cells by using a confocal fluorescence microscope. We find that the degradation of perovskite films starts from grain boundaries and gradually extend to the center of the grains. Firmly based on our findings, we further demonstrate that the device stability can be significantly enhanced by increasing the grain size of perovskite crystals. Our results have important implications to further enhance the stability of optoelectronic devices based on metal halide perovskites. Published by AIP Publishing.
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| 7. |
- Yang, Rong, et al.
(författare)
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Oriented Quasi-2D Perovskites for High Performance Optoelectronic Devices
- 2018
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 30:51
-
Tidskriftsartikel (refereegranskat)abstract
- Quasi-2D layered organometal halide perovskites have recently emerged as promising candidates for solar cells, because of their intrinsic stability compared to 3D analogs. However, relatively low power conversion efficiency (PCE) limits the application of 2D layered perovskites in photovoltaics, due to large energy band gap, high exciton binding energy, and poor interlayer charge transport. Here, efficient and water-stable quasi-2D perovskite solar cells with a peak PCE of 18.20% by using 3-bromobenzylammonium iodide are demonstrated. The unencapsulated devices sustain over 82% of their initial efficiency after 2400 h under relative humidity of approximate to 40%, and show almost unchanged photovoltaic parameters after immersion into water for 60 s. The robust performance of perovskite solar cells results from the quasi-2D perovskite films with hydrophobic nature and a high degree of electronic order and high crystallinity, which consists of both ordered large-bandgap perovskites with the vertical growth in the bottom region and oriented small-bandgap components in the top region. Moreover, due to the suppressed nonradiative recombination, the unencapsulated photovoltaic devices can work well as light-emitting diodes (LEDs), exhibiting an external quantum efficiency of 3.85% and a long operational lifetime of approximate to 96 h at a high current density of 200 mA cm(-2) in air.
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| 8. |
- Bao, Chunxiong, et al.
(författare)
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A multifunctional display based on photo-responsive perovskite light-emitting diodes
- 2024
-
Ingår i: NATURE ELECTRONICS. - : NATURE PORTFOLIO. - 2520-1131.
-
Tidskriftsartikel (refereegranskat)abstract
- Current display screens are typically only used for information display, but can have a range of different sensors integrated into them for functions such as touch control, ambient light sensing and fingerprint sensing. Photo-responsive light-emitting diodes (LEDs), which can display information and respond to light excitation, could be used to develop future ultra-thin and large screen-to-body ratio screens. However, photo-response is difficult to achieve with conventional display technologies. Here, we report a multifunctional display that uses photo-responsive metal halide perovskite LEDs as pixels. The perovskite LED display can be simultaneously used as a touch screen, ambient light sensor and image sensor (including for fingerprint drawing) without integrating any additional sensors. The light-to-electricity conversion efficiency of the pixels also allow the display to act as a photovoltaic device that can charge the equipment. Photo-responsive metal halide perovskite light-emitting diodes can be used to create a multifunctional display that can function as a touch screen, ambient light sensor and image sensor.
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| 9. |
- Kuang, Chaoyang, et al.
(författare)
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Critical role of additive-induced molecular interaction on the operational stability of perovskite light-emitting diodes
- 2021
-
Ingår i: Joule. - : Cell Press. - 2542-4351. ; 5:3, s. 618-630
-
Tidskriftsartikel (refereegranskat)abstract
- Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs.
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| 10. |
- Wang, Kang, et al.
(författare)
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Luminescent metal-halide perovskites: fundamentals, synthesis, and light-emitting devices
- 2024
-
Ingår i: Science in China Series B. - : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 67:6, s. 1776-1838
-
Forskningsöversikt (refereegranskat)abstract
- Metal-halide perovskites have garnered considerable research attention as highly efficient light emitters in recent years due to their outstanding optoelectronic properties with remarkable tunability and excellent solution processabilities. Substantial advancements have been achieved in the development of novel halide perovskites, and the exploitations of these materials in light-emitting devices. This review comprehensively outlines recent breakthroughs in metal-halide perovskites, encompassing the rational design of perovskite materials with tunable light emission properties, the controllable growth of single crystal for a deeper understanding of their structure-property relationships, as well as the fundamental insights into the photophysics and carrier dynamics in perovskite systems. Additionally, it provides an overview of recent applications of perovskite materials in high-performance light-emitting diodes (LEDs) and lasers.
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| 11. |
- Wang, Nana, et al.
(författare)
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Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells
- 2016
-
Ingår i: Nature Photonics. - : NATURE PUBLISHING GROUP. - 1749-4885 .- 1749-4893. ; 10:11, s. 699-
-
Tidskriftsartikel (refereegranskat)abstract
- Organometal halide perovskites can be processed from solutions at low temperatures to form crystalline direct-bandgap semiconductors with promising optoelectronic properties(1-5). However, the efficiency of their electroluminescence is limited by non-radiative recombination, which is associated with defects and leakage current due to incomplete surface coverage(6-9). Here we demonstrate a solution-processed perovskite light-emitting diode (LED) based on self-organized multiple quantum wells (MQWs) with excellent film morphologies. The MQW-based LED exhibits a very high external quantum efficiency of up to 11.7%, good stability and exceptional highpower performance with an energy conversion efficiency of 5.5% at a current density of 100 mA cm(-2). This outstanding performance arises because the lower bandgap regions that generate electroluminescence are effectively confined by perovskite MQWs with higher energy gaps, resulting in very efficient radiative decay. Surprisingly, there is no evidence that the large interfacial areas between different bandgap regions cause luminescence quenching.
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| 12. |
- Xu, Weidong, 1988-, et al.
(författare)
-
Rational molecular passivation for high-performance perovskite light-emitting diodes
- 2019
-
Ingår i: Nature Photonics. - : Springer Nature Publishing AG. - 1749-4885 .- 1749-4893. ; 13:6, s. 418-424
-
Tidskriftsartikel (refereegranskat)abstract
- A major efficiency limit for solution-processed perovskite optoelectronic devices, for example light-emitting diodes, is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures influence the effectiveness of passivation. We show that the so far largely ignored hydrogen bonds play a critical role in affecting the passivation. By weakening the hydrogen bonding between the passivating functional moieties and the organic cation featuring in the perovskite, we significantly enhance the interaction with defect sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near-infrared perovskite light-emitting diodes with a record external quantum efficiency of 21.6%. In addition, our passivated perovskite light-emitting diodes maintain a high external quantum efficiency of 20.1% and a wall-plug efficiency of 11.0% at a high current density of 200 mA cm−2, making them more attractive than the most efficient organic and quantum-dot light-emitting diodes at high excitations.
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| 13. |
- Yu, Hongling, et al.
(författare)
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Color-Stable Blue Light-Emitting Diodes Enabled by Effective Passivation of Mixed Halide Perovskites
- 2021
-
Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 12:26, s. 6041-6047
-
Tidskriftsartikel (refereegranskat)abstract
- Bandgap tuning through mixing halide anions is one of the most attractive features for metal halide perovskites. However, mixed halide perovskites usually suffer from phase segregation under electrical biases. Herein, we obtain high-performance and color-stable blue perovskite LEDs (PeLEDs) based on mixed bromide/ chloride three-dimensional (3D) structures. We demonstrate that the color instability of CsPb(Br1-xClx)(3) PeLEDs results from surface defects at perovskite grain boundaries. By effective defect passivation, we achieve color-stable blue electroluminescence from CsPb(Br1-xClx)(3) PeLEDs, with maximum external quantum efficiencies of up to 4.5% and high luminance of up to 5351 cd m(-2) in the sky-blue region (489 nm). Our work provides new insights into the color instability issue of mixed halide perovskites and can spur new development of high-performance and color-stable blue PeLEDs.
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| 14. |
- Yu, Hongling, et al.
(författare)
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Efficient and Tunable Electroluminescence from In Situ Synthesized Perovskite Quantum Dots
- 2019
-
Ingår i: Small. - : WILEY-V C H VERLAG GMBH. - 1613-6810 .- 1613-6829. ; 15:8
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconductor quantum dots (QDs) are among the most promising next-generation optoelectronic materials. QDs are generally obtained through either epitaxial or colloidal growth and carry the promise for solution-processed high-performance optoelectronic devices such as light-emitting diodes (LEDs), solar cells, etc. Herein, a straightforward approach to synthesize perovskite QDs and demonstrate their applications in efficient LEDs is reported. The perovskite QDs with controllable crystal sizes and properties are in situ synthesized through one-step spin-coating from perovskite precursor solutions followed by thermal annealing. These perovskite QDs feature size-dependent quantum confinement effect (with readily tunable emissions) and radiative monomolecular recombination. Despite the substantial structural inhomogeneity, the in situ generated perovskite QDs films emit narrow-bandwidth emission and high color stability due to efficient energy transfer between nanostructures that sweeps away the unfavorable disorder effects. Based on these materials, efficient LEDs with external quantum efficiencies up to 11.0% are realized. This makes the technologically appealing in situ approach promising for further development of state-of-the-art LED systems and other optoelectronic devices.
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| 15. |
- Zhang, Liangdong, et al.
(författare)
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Bright Free Exciton Electroluminescence from Mn-Doped Two-Dimensional Layered Perovskites
- 2019
-
Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 10:11, s. 3171-3175
-
Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) perovskites incorporating hydrophobic organic spacer cations show improved film stability and morphology compared to their three-dimensional (3D) counterparts. However, 2D perovskites usually exhibit low photoluminescence quantum efficiency (PLQE) owing to strong exciton-phonon interaction at room temperature, which limits their efficiency in light-emitting diodes (LEDs). Here, we demonstrate that the device performance of 2D perovskite LEDs can be significantly enhanced by doping Mn(2+)in (benzimidazolium)(2)PbI4 2D perovskite films to suppress the exciton-phonon interaction. The distorted [PbI6](4-) octahedra by Mn-doping and the rigid benzimidazolium (BIZ) ring without branched chains in the 2D perovskite structure lead to improved crystallinity and rigidity of the perovskites, resulting in suppressed phonon-exciton interaction and enhanced PLQE. On the basis of this strategy, for the first time, we report yellow electroluminescence from free excitons in 2D (n = 1) perovskites with a maximum brightness of 225 cd m(-2) and a peak EQE of 0.045%.
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| 16. |
- Zhang, Liang, et al.
(författare)
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Deep Learning for Additive Screening in Perovskite Light-Emitting Diodes
- 2022
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 61:37
-
Tidskriftsartikel (refereegranskat)abstract
- Additive engineering with organic molecules is of critical importance for achieving high-performance perovskite optoelectronic devices. However, experimentally finding suitable additives is costly and time consuming, while conventional machine learning (ML) is difficult to predict accurately due to the limited experimental data available in this relatively new field. Here, we demonstrate a deep learning method that can predict the effectiveness of additives in perovskite light-emitting diodes (PeLEDs) with a high accuracy up to 96 % by using a small dataset of 132 molecules. This model can maximize the information of the molecules and significantly mitigate the duplicated problem that usually happened with previous models in ML for molecular screening. Very high efficiency PeLEDs with a peak external quantum efficiency up to 22.7 % can be achieved by using the predicated additive. Our work opens a new avenue for further boosting the performance of perovskite optoelectronic devices.
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| 17. |
- Zou, Wei, et al.
(författare)
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Minimising efficiency roll-off in high-brightness perovskite light-emitting diodes
- 2018
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Efficiency roll-off is a major issue for most types of light-emitting diodes (LEDs), and its origins remain controversial. Here we present investigations of the efficiency roll-off in perovskite LEDs based on two-dimensional layered perovskites. By simultaneously measuring electroluminescence and photoluminescence on a working device, supported by transient photoluminescence decay measurements, we conclude that the efficiency roll-off in perovskite LEDs is mainly due to luminescence quenching which is likely caused by non-radiative Auger recombination. This detrimental effect can be suppressed by increasing the width of quantum wells, which can be easily realized in the layered perovskites by tuning the ratio of large and small organic cations in the precursor solution. This approach leads to the realization of a perovskite LED with a record external quantum efficiency of 12.7%, and the efficiency remains to be high, at approximately 10%, under a high current density of 500 mA cm(-2).
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| 18. |
- Abu-Zidan, FM, et al.
(författare)
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Establishment of a teaching animal model for sonographic diagnosis of trauma
- 2004
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Ingår i: Journal of Trauma. - 0022-5282 .- 1529-8809. ; 56:1, s. 99-104
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ultrasound is widely accepted as a valuable diagnostic tool for detecting intra-abdominal and intrathoracic bleeding in trauma patients. Nevertheless, many doctors are reluctant to use it because they do not have sufficient training. This study aimed to define intraabdominal and intrathoracic fluid volumes that can be detected by sonography and their relation to fluid width in pigs to establish a clinically relevant animal model for teaching and training. Methods: Different volumes of normal saline were infused into the abdomen (50-2,000 mL) and chest (25-250 mL) in five anesthetized pigs. The maximum width of fluid as detected by ultrasound was recorded. The right upper quadrant, left upper quadrant, pelvis, and right paracolic section of the abdomen and right pleural cavity were studied. An experienced radiologist performed the studies. The effects on respiratory and cardiovascular functions were evaluated. Results: The sonographic findings in the pig were similar to those in humans. Up to 50 mL of intra-abdominal fluid and up to 25 mL of intrathoracic fluid could be detected by ultrasound. There was a significant correlation between the volume infused and the fluid width detected. The respiratory and cardiovascular monitoring of the animals showed that the infused intrathoracic volumes mimicked a survivable hemothorax. Conclusion: The pig may serve as an excellent clinically relevant model with which to teach surgeons detection of different volumes of intra-abdominal and intrathoracic fluids. The value of this model as an educational tool has yet to be tested.
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| 19. |
- Bai, Sai, et al.
(författare)
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Ethanedithiol Treatment of Solution-Processed ZnO Thin Films: Controlling the Intragap States of Electron Transporting Interlayers for Efficient and Stable Inverted Organic Photovoltaics
- 2015
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Ingår i: Advanced Energy Materials. - : Wiley-VCH Verlag. - 1614-6832 .- 1614-6840. ; 5:5, s. 1401606-
-
Tidskriftsartikel (refereegranskat)abstract
- The surface defects of solution-processed ZnO films lead to various intragap states. When the solution-processed ZnO films are used as electron transport interlayers (ETLs) in inverted organic solar cells, the intragap states act as interfacial recombination centers for photogenerated charges and thereby degrade the device performance. Here, a simple passivation method based on ethanedithiol (EDT) treatment is demonstrated, which effectively removes the surface defects of the ZnO nanocrystal films by forming zinc ethanedithiolates. The passivation by EDT treatment modulates the intragap states of the ZnO films and introduces a new intragap band. When the EDT-treated ZnO nanocrystal films are used as ETLs in inverted organic solar cells, both the power conversion efficiency and stability of the devices are improved. The control studies show that the solar cells with EDT-treated ZnO films exhibit reduced charge recombination rates and enhanced charge extraction properties. These features are consistent with the fact that the modulation of the intragap states results in reduction of interfacial recombination as well as the improved charge selectivity and electron transport properties of the ETLs. It is further demonstrated that the EDT treatment-based passivation method can be extended to ZnO films deposited from sol-gel precursors.
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| 20. |
- Bao, Chunxiong, et al.
(författare)
-
Bidirectional optical signal transmission between two identical devices using perovskite diodes
- 2020
-
Ingår i: NATURE ELECTRONICS. - : NATURE PUBLISHING GROUP. - 2520-1131. ; 3:3, s. 156-164
-
Tidskriftsartikel (refereegranskat)abstract
- A solution-processed perovskite diode that functions as both optical transmitter and receiver can be used to build a monolithic pulse sensor and a bidirectional optical communication system. The integration of optical signal generation and reception into one device-thus allowing a bidirectional optical signal transmission between two identical devices-is of value in the development of miniaturized and integrated optoelectronic devices. However, conventional solution-processable semiconductors have intrinsic material and design limitations that prevent them from being used to create such devices with a high performance. Here we report an efficient solution-processed perovskite diode that is capable of working in both emission and detection modes. The device can be switched between modes by changing the bias direction, and it exhibits light emission with an external quantum efficiency of over 21% and a light detection limit on a subpicowatt scale. The operation speed for both functions can reach tens of megahertz. Benefiting from the small Stokes shift of perovskites, our diodes exhibit a high specific detectivity (more than 2 x 10(12) Jones) at its peak emission (~804 nm), which allows an optical signal exchange between two identical diodes. To illustrate the potential of the dual-functional diode, we show that it can be used to create a monolithic pulse sensor and a bidirectional optical communication system.
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| 21. |
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| 22. |
- Gao, Feng, et al.
(författare)
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Temperature Dependence of Charge Carrier Generation in Organic Photovoltaics
- 2015
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 114:12, s. 128701-
-
Tidskriftsartikel (refereegranskat)abstract
- The charge generation mechanism in organic photovoltaics is a fundamental yet heavily debated issue. All the generated charges recombine at the open-circuit voltage (VOC), so that investigation of recombined charges at VOC provides a unique approach to understanding charge generation. At low temperatures, we observe a decrease of VOC, which is attributed to reduced charge separation. Comparison between benchmark polymer: fullerene and polymer: polymer blends highlights the critical role of charge delocalization in charge separation and emphasizes the importance of entropy in charge generation.
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| 23. |
- Gao, Feng, et al.
(författare)
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The Effect of Processing Additives on Energetic Disorder in Highly Efficient Organic Photovoltaics : A Case Study on PBDTTT-C-T:PC71BM
- 2015
-
Ingår i: Advanced Materials. - : Wiley-VCH Verlag. - 0935-9648 .- 1521-4095. ; 27:26, s. 3868-3873
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Tidskriftsartikel (refereegranskat)abstract
- Energetic disorder, an important parameter affecting the performance of organic photovoltaics, is significantly decreased upon the addition of processing additives in a highly efficient benzodithiophene-based copolymer blend (PBDTTT-C-T:PC71BM). Wide-angle and small-angle X-ray scattering measurements suggest that the origin of this reduced energetic disorder is due to increased aggregation and a larger average fullerene domain size together with purer phases.
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| 24. |
- Gao, Feng, et al.
(författare)
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The renaissance of hybrid solar cells : progresses, challenges, and perspectives
- 2013
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 6:7, s. 2020-2040
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Forskningsöversikt (refereegranskat)abstract
- Solution-processed hybrid solar cells, a blend of conjugated polymers and semiconducting nanocrystals, are a promising candidate for next-generation energy-conversion devices. The renaissance of this field in recent years has yielded a much deeper understanding of optoelectronic interactions in organic–inorganic hybrid systems. In this article, we review the state-of-the-art progress in hybrid bulk heterojunction solar cells, covering new materials design, interfacial interaction, and processing control. Furthermore, critical challenges that determine photovoltaic performance and prospects for future directions are discussed.
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| 25. |
- Gao, Feng, et al.
(författare)
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Trap-Induced Losses in Hybrid Photovoltaics
- 2014
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Ingår i: ACS Nano. - : American Chemical Society. - 1936-0851 .- 1936-086X. ; 8:4, s. 3213-3221
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the loss mechanisms in hybrid photovoltaics based on blends of poly(3-hexylthiophene) with CdSe nanocrystals of various sizes. By combining the spectroscopic and electrical measurements on working devices as well as films, we identify that high trap-mediated recombination is responsible for the loss of photogenerated charge carriers in devices with small nanocrystals. In addition, we demonstrate that the reduced open-circuit voltage for devices with small nanocrystals is also caused by the traps.
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| 26. |
- Giuri, Antonella, et al.
(författare)
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Ultra-Bright Near-Infrared Perovskite Light-Emitting Diodes with Reduced Efficiency Roll-off
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, an insulating biopolymer is exploited to guide the controlled formation of micro/nano-structure and physical confinement of alpha-delta mixed phase crystalline grains of formamidinium lead iodide (FAPbI(3)) perovskite, functioning as charge carrier concentrators and ensuring improved radiative recombination and photoluminescence quantum yield (PLQY). This composite material is used to build highly efficient near-infrared (NIR) FAPbI(3) Perovskite light-emitting diodes (PeLEDs) that exhibit a high radiance of 206.7 W/sr*m(2), among the highest reported for NIR-PeLEDs, obtained at a very high current density of 1000 mA/cm(2), while importantly avoiding the efficiency roll-off effect. In depth photophysical characterization allows to identify the possible role of the biopolymer in i) enhancing the radiative recombination coefficient, improving light extraction by reducing the refractive index, or ii) enhancing the effective optical absorption because of dielectric scattering at the polymer-perovskite interfaces. Our study reveals how the use of insulating matrixes for the growth of perovskites represents a step towards high power applications of PeLEDs.
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| 27. |
- Lin, Jianpu, et al.
(författare)
-
Image segmentation by improved minimum spanning tree with fractional differential and Canny detector
- 2019
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Ingår i: Journal of Algorithms and Computational Technology. - : SAGE PUBLICATIONS LTD. - 1748-3018 .- 1748-3026. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we propose an algorithm that uses an improved Minimum Spanning Tree algorithm and a modified Canny edge detector to segment images that contain a considerable amount of noises. First, we use our modified Canny operator to pre-process an image, and record the obtained object boundary information; then, we apply the improved Minimum Spanning Tree algorithm to associate the above information with boundary points in order to separate edges into two classes in the image, namely the inner and boundary regions. In particular, Minimum Spanning Tree algorithm is improved by using Fractional differential and combining the functions of the intra-regional and inter-regional differences with a function for edge weights. Based on the experimental results, compared with the other four exiting algorithms, the new algorithm has the higher accuracy and the better effect for noised image segmentation.
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| 28. |
- Liu, Xiaoke, et al.
(författare)
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Metal halide perovskites for light-emitting diodes
- 2021
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Ingår i: Nature Materials. - : NATURE PUBLISHING GROUP. - 1476-1122 .- 1476-4660. ; 20:1, s. 10-21
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Forskningsöversikt (refereegranskat)abstract
- The development of perovskite emitters, their use in light-emitting devices, and the challenges in enhancing the efficiency and stability, as well as reducing the potential toxicity of this technology are discussed in this Review. Metal halide perovskites have shown promising optoelectronic properties suitable for light-emitting applications. The development of perovskite light-emitting diodes (PeLEDs) has progressed rapidly over the past several years, reaching high external quantum efficiencies of over 20%. In this Review, we focus on the key requirements for high-performance PeLEDs, highlight recent advances on materials and devices, and emphasize the importance of reliable characterization of PeLEDs. We discuss possible approaches to improve the performance of blue and red PeLEDs, increase the long-term operational stability and reduce toxicity hazards. We also provide an overview of the application space made possible by recent developments in high-efficiency PeLEDs.
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| 29. |
- Olofsson, Pia, 1962-, et al.
(författare)
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The effects of early rapid control of multiple bowel perforations after high-energy trauma to the abdomen : implications for damage control surgery
- 2006
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Ingår i: Journal of Trauma. - : Ovid Technologies (Wolters Kluwer Health). - 0022-5282 .- 1529-8809. ; 61:1, s. 185-191
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: This study evaluates the effects of early rapid control of multiple bowel perforations on cardiovascular and pulmonary function in high-energy traumatic shock compared with conventional small bowel resection anastomosis. METHODS: Fifteen anesthetized pigs, 10 to 12 weeks old, were exposed to a reproducible high-energy trauma and were divided into two groups. In the first group, the resection anastomosis group (RA, n = 8), small-bowel injuries were treated with resection and anastomosis; in the second group, the multiple bowel ligation group (BL, n = 7), small-bowel injuries were treated by resection and ligation. Repeated measurement analysis of variance was used to study the within group change overtime, the between group difference, and the interaction between them. Mean outcome measures were intravascular pressures, cardiac output, vascular resistance, lactic acid, and blood gases. RESULTS: The high-energy injuries caused traumatic shock in both groups with reduced cardiac output (p < 0.001) and lactic acidemia (p < 0.001). The BL group had a trend for higher cardiac output (p = 0.06). The rise in systemic and pulmonary vascular resistance was significantly reduced in the BL group compared with the RA group (p < 0.05). The BL group had a strong trend for higher oxygen extraction ratio (p = 0.06). There was a trend for less oxygen consumption in the BL group (p = 0.07). There was no difference in the lactic acidemia between the two groups. CONCLUSIONS: Early rapid control of multiple bowel perforations after high-energy trauma resulted in less impairment of cardiovascular function than conventional resection anastomosis of the bowel.
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| 30. |
- Shi, Xiaobo, et al.
(författare)
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Optical Energy Losses in Organic-Inorganic Hybrid Perovskite Light-Emitting Diodes
- 2018
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Ingår i: Advanced Optical Materials. - : John Wiley & Sons. - 2162-7568 .- 2195-1071. ; 6:17
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Tidskriftsartikel (refereegranskat)abstract
- Light-emitting diodes (LEDs) based on organic-inorganic hybrid perovskites, in particular, 3D and quasi-2D ones, are in the fast development and their external quantum efficiencies (EQEs) have exceeded 10%, making them competitive candidates toward large-area and low-cost light-emitting applications allowing printing techniques. Similar to other LED categories, light out-coupling efficiency is an important parameter determining the EQE of perovskite LEDs (PeLEDs), which, however, is scarcely studied, limiting further efficiency improvement and understanding of PeLEDs. In this work, for the first time, optical energy losses in PeLEDs are investigated through systematic optical simulations, which reveal that the 3D and quasi-2D PeLEDs can achieve theoretically maximum EQEs of approximate to 25% and approximate to 20%, respectively, in spite of their high refractive indices. These results are consistent with the reported experimental data. This work presents primary understanding of the optical energy losses in PeLEDs and will spur new developments in the aspects of device engineering and light extraction techniques to boost the EQEs of PeLEDs.
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| 31. |
- Wang, Jianpu, et al.
(författare)
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Administration of aerosolized terbutaline and budesonide reduces chlorine gas-induced acute lung injury
- 2004
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Ingår i: Journal of Trauma. - 0022-5282 .- 1529-8809. ; 56:4, s. 850-862
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Tidskriftsartikel (refereegranskat)abstract
- Background: The pathophysiology and treatment of chlorine gas-induced acute lung injury is poorly characterized and based on anecdotal data. This study aimed to assess the effects of aerosolized beta-2 adrenergic agonist and corticosteroid therapy on chlorine gas-induced lung injury.Methods: Anesthetized, ventilated pigs were exposed to chlorine gas (400 parts per million for 20 minutes), then assigned randomly 30 minutes later to receive aerosolized terbutaline, budesonide, terbutaline followed by budesonide or placebo (6 pigs in each group). Hemodynamics, gas exchange, and lung mechanics were evaluated for another 5 hours.Results: All the animals demonstrated an immediate increase in airway and pulmonary artery pressure as well as sharp drops in arterial oxygen tension (PaO2) and lung compliance (C L). Recovery of PaO2 and CL was greatest in the terbutaline plus budesonide group, but therapy with terbutaline and budesonide alone also was associated with significant improvement in PaO2 and CL, as compared with placebo.Conclusions. Treatment of acute chlorine gas lung injury with aerosolized terbutaline followed by aerosolized budesonide improved lung function. Combined treatment was more effective than treatment with either drug alone.
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| 32. |
- Wang, Jianpu, et al.
(författare)
-
Control of exciton spin statistics through spin polarization in organic optoelectronic devices
- 2012
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Ingår i: Nature Communications. - : Nature Publishing Group: Nature Communications. - 2041-1723. ; 3:1191
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Tidskriftsartikel (refereegranskat)abstract
- Spintronics based on organic semiconductor materials is attractive because of its rich fundamental physics and potential for device applications. Manipulating spins is obviously important for spintronics, and is usually achieved by using magnetic electrodes. Here we show a new approach where spin populations can be controlled primarily by energetics rather than kinetics. We find that exciton spin statistics can be substantially controlled by spin-polarizing carriers after injection using high magnetic fields and low temperatures, where the Zeeman energy is comparable with the thermal energy. By using this method, we demonstrate that singlet exciton formation can be suppressed by up to 53% in organic light-emitting diodes, and the dark conductance of organic photovoltaic devices can be increased by up to 45% due to enhanced formation of triplet charge-transfer states, leading to less recombination to the ground state.
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| 33. |
- Wang, Jianpu, 1957-, et al.
(författare)
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Effects of endothelin receptor antagonism on acute lung injury induced by chlorine gas
- 2006
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 34:6, s. 1731-1737
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To test the hypothesis that the endothelin system is involved in chlorine gas-induced lung injury.DESIGN: Experimental study.SETTING: Academic research laboratory.SUBJECTS: Twenty-four domestic juvenile pigs.INTERVENTIONS: Anesthetized, ventilated pigs were exposed to chlorine gas (400 parts per million in air) for 20 mins and then randomly allocated to four groups (n = 6 in each group). The tezosentan pretreatment group received the dual endothelin receptor antagonist tezosentan 20 mins before and hyperoxic gas (Fio2 0.6) after chlorine gas exposure. The tezosentan postinjury treatment group received hyperoxic gas after chlorine gas exposure and tezosentan 60 mins later. Animals in the oxygen group received hyperoxic gas after chlorine gas exposure. Pigs in the fourth group (air) were ventilated with room air (Fio2 0.21) throughout the experiment.MEASUREMENTS AND MAIN RESULTS: Hemodynamics, gas exchange, lung mechanics, and plasma endothelin-1 were evaluated for 6 hrs. Chlorine gas exposure induced an increase in circulating endothelin-1 by 90% (p < .05). The acute chlorine gas-induced rise in pulmonary vascular resistance was partly blocked by tezosentan pretreatment (p < .001). Tezosentan postinjury treatment also decreased pulmonary vascular resistance to levels significantly lower than in the air and oxygen groups (p < .001). Recovery of peak airway pressure was better in the tezosentan-treated groups than in the air group. There were significant linear relationships between circulating endothelin-1 and pulmonary vascular resistance (r = .47, p < .001) and endothelin-1 and peak airway pressure (r = .41, p < .001). These relationships were modified by tezosentan.CONCLUSIONS: Tezosentan modified chlorine gas-induced pulmonary dysfunction, indicating that the endothelin system is involved in this mode of acute lung injury.
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| 34. |
- Wang, Jianpu, 1957-, et al.
(författare)
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Effects of prone and supine posture on cardiopulmonary function after experimental chlorine gas lung injury
- 2002
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 46:9, s. 1094-1102
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Tidskriftsartikel (refereegranskat)abstract
- Background: Chlorine gas may induce severe acute lung injury. Improvement of pulmonary gas exchange in patients and animals with acute lung injury nursed in the prone position was observed in recent years. The purpose of this study was to evaluate the effects of prone and supine positions on pulmonary and cardiovascular functions following experimental chlorine gas lung injury.Methods: Twenty anesthetized and mechanically ventilated pigs were exposed to chlorine gas (400 p.p.m. in air) for 20 min in the supine position, then assigned randomly to ventilation in the supine or prone positions (n=10 in each group). Hemodynamics, gas exchange, lung mechanics and oxygen transport were evaluated for 5 h.Results: All animals showed severe pulmonary dysfunction immediately after chlorine gassing with a threefold increase in pulmonary vascular resistance index, a drop in arterial oxygenation (12.3±1.3 kPa to 5.4±0.7 kPa) and a fall in lung-thorax compliance (22±1 ml cmH2O−1 to 8±2 ml cmH2O−1). Venous admixture (Qs/Qt) improved in animals in the prone position while there was no change in the supine position (prone 32±11% vs. supine 42±9% at 5 h,P<0.05). Lung-thorax compliance improved significantly with time in the prone group only (P<0.01). Oxygen delivery increased significantly in prone animals compared with animals nursed in the supine posture (P<0.001).Conclusion: Immediate prone positioning after chlorine gas injury not only inhibited deterioration of gas exchange but was also associated with improved pulmonary function and oxygen transport.
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| 35. |
- Wang, Jianpu, et al.
(författare)
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Entirely solution-processed write-once-read-many-times memory devices and their operation mechanism
- 2011
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Ingår i: Organic electronics. - : Elsevier. - 1566-1199 .- 1878-5530. ; 12:7, s. 1271-1274
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the mechanism of operation of low-power write-once-read-many-times (WORM) memory devices based on injection of electrons from ZnO into PEDOT:PSS (polydioxythiophene doped with polystyrenesulfonic acid). Using Raman spectroscopy and in situ absorbance measurements, we directly observe the change of doping level of PEDOT during the device switching. Our results clearly show that the change of device conductance is due to the dedoping of p-doped PEDOT by injected electrons. Based on this understanding, we further demonstrate an entirely solution-processed low-power WORM device by inkjet printing metal electrodes onto arbitrary substrates. (C) 2011 Elsevier B.V. All rights reserved.
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| 36. |
- Wang, Jianpu, et al.
(författare)
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Inhaled and intravenous corticosteroids both attenuate chlorine gas-induced lung injury in pigs
- 2005
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 49:2, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- Background: The accidental release of chlorine gas is a constant threat in urban areas. The purpose of this randomized, blinded, controlled experiment was to examine the effects of post-injury administration of inhaled or intravenous corticosteroid in chlorine gas-injured pigs followed for 23 h.Methods: Anaesthetized, ventilated pigs (n = 24) in the prone position were exposed to chlorine gas (400 parts per million in air) (1160 mg/m3) for 15 min, then randomly allocated to receive inhaled budesonide (BUD) and intravenous placebo, intravenous betamethasone (BETA) and inhaled placebo or inhaled and intravenous placebo. Haemodynamics, gas exchange and lung mechanics were evaluated for 23 h after exposure to chlorine gas.Results: Airway and pulmonary artery pressures increased and arterial oxygenation fell sharply (from 13.5 ± 0.8 to 6.7 ± 0.9 kPa, P < 0.001) after chlorine gas exposure. These immediate changes were followed by a gradual improvement over 5–7 h to a stable level of dysfunction for the rest of the experiment in placebo animals. Arterial oxygen tension, pulmonary vascular resistance and airway pressure recovered faster and more completely in the budesonide and betamethasone groups than in the placebo group (P < 0.01). Lung wet weight to dry weight ratios were greater in the placebo group than in the budesonide and betamethasone groups (6.34 ± 0.59 vs. 5.56 ± 0.38 and 5.53 ± 0.54, respectively, P < 0.05). There was a trend towards lower histological injury scores compared with placebo in animals that received budesonide (P = 0.05) or betamethasone (P = 0.07).Conclusion: Treatment of chlorine gas lung injury with nebulized budesonide or intravenous betamethasone had similar positive effects on recovery of lung function.
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| 37. |
- Wang, Jianpu, 1957-, et al.
(författare)
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Inhaled budesonide in experimental chlorine gas lung injury : influence of time interval between injury and treatment
- 2002
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Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 28:3, s. 352-357
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To examine the time window between injury and treatment during which nebulized corticosteroid lessens lung injury induced by chlorine gas inhalation.Design: An experimental laboratory study.Setting: Academic research laboratory.Subjects: Twenty-four juvenile female pigs.Interventions: Twenty-four mechanically ventilated pigs were exposed to chlorine gas (400 PPM in air) for 20 min, then divided into four groups (six in each group). Nebulized budesonide (BUD) was given immediately (BUD 0 min), 30 min (BUD 30 min) or 60 min (BUD 60 min) after chlorine gas exposure. Six pigs receiving nebulized saline served as controls.Measurements and main results: Hemodynamics, gas exchange and lung mechanics were evaluated for 5 h after chlorine gas exposure. All animals had an immediate increase in airway and pulmonary artery pressure and a sharp drop of arterial oxygenation. The mean arterial oxygen tension of BUD 0 min and BUD 30 min animals was significantly higher than in the control and the BUD 60 min groups (p<0.001). The recovery of lung compliance in the BUD 0 min and the BUD 30 min groups was significantly more rapid than in the control and the BUD 60 min groups (p<0.001). The pulmonary wet to dry weight ratio was greater in the control group than in the BUD-treated groups (p<0.05).Conclusion: Treatment with inhaled budesonide immediately or 30 min after chlorine gas lung injury had similar positive effects on symptoms and signs of pulmonary injury, whereas treatment delayed for 60 min was less effective.
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| 38. |
- Wang, Jianpu, et al.
(författare)
-
Low-power write-once-read-many-times memory devices
- 2010
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 97:5
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Tidskriftsartikel (refereegranskat)abstract
- We introduce low-power write-once-read-many-times memory devices fabricated from solution. These devices are based on an electron-only structure using colloidal ZnO semiconductor nanoparticles and the doped conjugated polymer polyethylenedioxythiophene doped with polystyrene sulfonic acid (PEDOT:PSS). The conductive p-doped conjugated polymer is permanently dedoped by injected electrons, producing an insulating state. This demonstration provides a class of memory devices with the potential for extremely low-cost, low-power-consumption applications, such as radio-frequency identification tags. (C) 2010 American Institute of Physics.
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| 39. |
- Wang, Jianpu, et al.
(författare)
-
Memristive devices based on solution-processed ZnO nanocrystals
- 2010
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlag. - 1862-6300 .- 1862-6319. ; 207:2, s. 484-487
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Tidskriftsartikel (refereegranskat)abstract
- We present a memristive device fabricated using low-cost solution-processed colloidal ZnO nanocrystals. Taking advantage of the large surface area of ZnO nanocrystals, we find that an oxygen depletion region can be naturally formed by chemical interaction between an Al electrode and the ZnO nanocrystals. Strong electrical hysteresis, history-dependent conductance, and sweep-rate-dependent current-voltage (J-V) curves are observed in our devices. The resistance can be modified between similar to 1 and similar to 10(4) Omega cm(2), which is promising for application in non-volatile memory devices and in low-cost organic circuits, where typical feature sizes are about 10-100 mu m and the circuit current is low. (C) 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim
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| 40. |
- Wang, Jianpu, 1957-
(författare)
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Pathophysiology and treatment of chlorine gas-induced lung injury : an experimental study in pigs
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the most threatening scenarios in disaster medicine is the accidental release of toxic gases with the exposure of many people. In this respect, chlorine gas remains a significant threat due to its abundant use and transport through densely populated areas in modem society. Access to a simple and effective method of treatment that could be started early would be of great value. The main purpose of this study was to test a series of hypotheses related to chlorine gas lung injury and its treatment.Anesthetized and mechanically ventilated pigs were exposed to chlorine gas (400 parts per million in air) using a closed system with a ventilator connected to gas cylinders. Plasma endothelin-1 (ET -1) and pro inflammatory cytokines were evaluated for 5 hours after injury while hemodynamics, gas exchange and lung mechanics were followed for 23 hours. Histopathology and lung water balance were assessed at the end of the experiment.Chlorine gas exposure induced a rise in circulating ET-1 and circulating cytokines (TNF-α, and IL-1ß, IL-6). Pretreatment or treatment with tezosentan, a potent dual endothelin receptor antagonist, reduced the deterioration of pulmonary function induced by chlorine gas inhalation. Immediate prone positioning after chlorine gas injury not only inhibited deterioration of gas exchange but was also associated with improved pulmonary function and oxygen transport. Nebulized budesonide given within 30 minutes after chlorine gas lung injury was effective in preventing further progression of lung dysfunction but the effect of treatment given beyond 60 minutes was less efficient. The positive effects on pulmonary function and lung water were similar whether corticosteroids were given by aerosol or intravenously. Combined treatment with nebulized terbutaline and budesonide was associated with better recovery of lung function than either drug alone.In conclusion, these studies outline the early pathophysiology of chlorine gas injury. They show that the endothelin system mediates the early pulmonary hypertensive and also to some extent the brochoconstrictive responses to inhaled chlorine gas. The work supports early administration of corticosteroids and ß2-agonists for individuals that are exposure to chlorine gas. In addition, early prone positioning of patients with severe chlorine gas lung injury may be useful.
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| 41. |
- Wang, Jianpu, et al.
(författare)
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The surface-state-induced Stark effect in ZnO nanocrystals
- 2010
-
Ingår i: Journal of Physics. - : IOP Publishing: Hybrid Open Access. - 0953-8984 .- 1361-648X. ; 22:39
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Tidskriftsartikel (refereegranskat)abstract
- Surface states in ZnO nanoparticles play an important role in controlling their electrical transport properties, and these properties can be modified greatly by exposure to UV light. In order to investigate the origin of these effects, we investigate the change in the optical absorption of films of ZnO nanoparticles on exposure to UV light. The modulation spectrum changes from the first derivative to the second derivative of the absorption spectrum as the films are annealed. UV illumination changes the surface states of the nanocrystals, leading to a change in the electric field within the films, which we study using electrostatic force microscopy. The modulation of the optical absorption is found to be consistent with a Stark effect caused by the change in the electric field.
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| 42. |
- Yang, Jie, et al.
(författare)
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Stable, High-Sensitivity and Fast-Response Photodetectors Based on Lead-Free Cs2AgBiBr6 Double Perovskite Films
- 2019
-
Ingår i: Advanced Optical Materials. - : WILEY-V C H VERLAG GMBH. - 2162-7568 .- 2195-1071. ; 7:13
-
Tidskriftsartikel (refereegranskat)abstract
- Solution-processed metal halide perovskites (MHPs) have demonstrated great advances on achieving high-performance photodetectors. However, the intrinsic material instability and the toxicity of lead still hinder the practical applications of MHPs-based photodetectors. In this work, the first highly sensitive and fast-response lead-free perovskite photodetectors based on Cs2AgBiBr6 double perovskite films are demonstrated. A convenient solution method is developed to deposit high-quality Cs2AgBiBr6 film with large grain sizes, low trap densities, and long charge carrier lifetimes. Incorporated within a photodiode device architecture comprised of optimized hole- and electron-transporting layers, lead-free perovskite photodetectors are achieved exhibiting a high detectivity of 3.29 x 10(12) Jones, a large linear dynamic range of 193 dB, and a fast response time of approximate to 17 ns. All the key figures of merit of the devices are comparable with the reported best-performing photodetectors based on lead halide perovskites. In addition, the resulting devices exhibit excellent thermal and environmental stability. The nonencapsulated devices show negligible degradation after thermal stressing at 150 degrees C and less than 5% degradation in the photoresponsivity after storage in ambient air for approximate to 2300 h. The results demonstrate the great potential of the lead-free Cs2AgBiBr6 double perovskite in applications for environmentally friendly and high-performance photodetectors.
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| 43. |
- Yi, Chang, et al.
(författare)
-
Intermediate-phase-assisted low-temperature formation of gamma-CsPbI3 films for high-efficiency deep-red light-emitting devices
- 2020
-
Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Black phase CsPbI3 is attractive for optoelectronic devices, while usually it has a high formation energy and requires an annealing temperature of above 300 degrees C. The formation energy can be significantly reduced by adding HI in the precursor. However, the resulting films are not suitable for light-emitting applications due to the high trap densities and low photoluminescence quantum efficiencies, and the low temperature formation mechanism is not well understood yet. Here, we demonstrate a general approach for deposition of gamma -CsPbI3 films at 100 degrees C with high photoluminescence quantum efficiencies by adding organic ammonium cations, and the resulting light-emitting diode exhibits an external quantum efficiency of 10.4% with suppressed efficiency roll-off. We reveal that the low-temperature crystallization process is due to the formation of low-dimensional intermediate states, and followed by interionic exchange. This work provides perspectives to tune phase transition pathway at low temperature for CsPbI3 device applications. Exploiting low-temperature formed black phase CsPbI3 for light-emitting applications remains a challenge. Here, the authors propose a method to enable the deposition of gamma -CsPbI3 films at 100C and demonstrate a light-emitting diode with an external quantum efficiency of 10.4% with suppressed efficiency roll-off.
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| 44. |
- Yuan, Zhongcheng, et al.
(författare)
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Unveiling the synergistic effect of precursor stoichiometry and interfacial reactions for perovskite light-emitting diodes
- 2019
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites are emerging as promising semiconductors for cost-effective and high-performance light-emitting diodes (LEDs). Previous investigations have focused on the optimisation of the emissive perovskite layer, for example, through quantum confinement to enhance the radiative recombination or through defect passivation to decrease non-radiative recombination. However, an in-depth understanding of how the buried charge transport layers affect the perovskite crystallisation, though of critical importance, is currently missing for perovskite LEDs. Here, we reveal synergistic effect of precursor stoichiometry and interfacial reactions for perovskite LEDs, and establish useful guidelines for rational device optimization. We reveal that efficient deprotonation of the undesirable organic cations by a metal oxide interlayer with a high isoelectric point is critical to promote the transition of intermediate phases to highly emissive perovskite films. Combining our findings with effective defect passivation of the active layer, we achieve high-efficiency perovskite LEDs with a maximum external quantum efficiency of 19.6%.
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| 45. |
- Zhao, Baodan, et al.
(författare)
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High-efficiency perovskite-polymer bulk heterostructure light-emitting diodes
- 2018
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Ingår i: Nature Photonics. - : NATURE PUBLISHING GROUP. - 1749-4885 .- 1749-4893. ; 12:12, s. 783-
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite-based optoelectronic devices are gaining much attention owing to their remarkable performance and low processing cost, particularly for solar cells. However, for perovskite light-emitting diodes, non-radiative charge recombination has limited the electroluminescence efficiency. Here we demonstrate perovskite-polymer bulk heterostructure light-emitting diodes exhibiting external quantum efficiencies of up to 20.1% (at current densities of 0.1-1 mA cm(-2)). The light-emitting diode emissive layer comprises quasi-two-dimensional and three-dimensional (2D/3D) perovskites and an insulating polymer. Photogenerated excitations migrate from quasi-2D to lower-energy sites within 1 ps, followed by radiative bimolecular recombination in the 3D regions. From near-unity external photoluminescence quantum efficiencies and transient kinetics of the emissive layer with and without charge-transport contacts, we find non-radiative recombination pathways to be effectively eliminated, consistent with optical models giving near 100% internal quantum efficiencies. Although the device brightness and stability (T-50 = 46 h in air at peak external quantum efficiency) require further improvement, our results indicate the significant potential of perovskite-based photon sources.
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