| 1. |
- Du, Siying, et al.
(författare)
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Nonfullerene acceptors from thieno[3,2-b]thiophene-fused naphthalene donor core with six-member-ring connection for efficient organic solar cells
- 2021
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Ingår i: Dyes and Pigments. - : Elsevier BV. - 0143-7208 .- 1873-3743. ; 185
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive design ideas on the fused-ring donor-core in state-of-the-art acceptor-donor-acceptor (A-D-A) nonfullerene acceptors (NFAs) are still of great importance for regulating the electron push-pull effect for the sake of optimal light-harvesting, frontier molecular orbital levels, and finally their photovoltaic properties. Herein, thieno[3,2-b]thiophenes were fused in bay-area of naphthalene via six-member-ring connection, resulting in the formation of dihydropyrenobisthieno[3,2-b]thiophene based octacyclic ladder-type donor core, which was flanked by two 1,1-dicyanomethylene-3-indanone (IC) acceptor motifs with and without 5,6-diflourination, namely PTT-IC and PTT-2FIC, respectively, as novel efficient A-D-A fused-ring electron acceptors (FREAs). Compared with PTT-IC, fluorinated PTT-2FIC possesses narrower optical bandgap of 1.48 eV, better π-π stacking, and its PBDB-T:PTT-2FIC blend film exhibited better morphology, and better hole and electron mobility. As a result, nonfullerene solar cells using PBDB-T:PTT-2FIC as the active layer achieved a decent PCE of 10.40%, with an open-circuit voltage (VOC) of 0.87 V, a fill factor (FF) of 0.65, and a much higher short-circuit current (JSC) of 18.26 mA/cm2. Meanwhile, the PBDB-T:PTT-IC cells delivered a lower JSC of 12.58 mA/cm2 but a higher VOC of 0.99 V, thus resulting in a PCE of 7.39% due to its wider optical bandgap of 1.58 eV and higher LUMO energy level. These results demonstrated that NFAs based on fused-ring donor core from fusing thieno[3,2-b]thiophenes with naphthalene via six-member-ring connection are promising for organic photovoltaic applications.
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| 2. |
- Hultmark, Sandra, 1994, et al.
(författare)
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Suppressing Co-Crystallization of Halogenated Non-Fullerene Acceptors for Thermally Stable Ternary Solar Cells
- 2020
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 30:48
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Tidskriftsartikel (refereegranskat)abstract
- While photovoltaic blends based on non-fullerene acceptors are touted for their thermal stability, this type of acceptor tends to crystallize, which can result in a gradual decrease in photovoltaic performance and affects the reproducibility of the devices. Two halogenated indacenodithienothiophene-based acceptors that readily co-crystallize upon mixing are studied, which indicates that the use of an acceptor mixture alone does not guarantee the formation of a disordered mixture. The addition of the donor polymer to the acceptor mixture readily suppresses the crystallization, which results in a fine-grained ternary blend with nanometer-sized domains that do not coarsen due to a high Tg ≈ 200 °C. As a result, annealing at temperatures of up to 170 °C does not markedly affect the photovoltaic performance of ternary devices, in contrast to binary devices that suffer from acceptor crystallization in the active layer. The results indicate that the ternary approach enables the use of high-temperature processing protocols, which are needed for upscaling and high-throughput fabrication of organic solar cells. Further, ternary devices display a stable photovoltaic performance at 130 °C for at least 205 h, which indicates that the use of acceptor mixtures allows to fabricate devices with excellent thermal stability.
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| 3. |
- Li, Li, et al.
(författare)
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Effects of 2-methoxyestradiol on endometrial carcinoma xenografts
- 2007
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Ingår i: Journal of Cancer Research and Clinical Oncology. - : Springer Science and Business Media LLC. - 0171-5216 .- 1432-1335. ; 133:5, s. 315-320
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We have previously demonstrated that 2-methoxyestradiol (2-ME) inhibits the growth of human endometrial cancer HEC-1-A and RL-95-2 cells in vitro. In this study, we examined the effects of 2-ME on human endometrial carcinoma in severe combined immune deficient (SCID) mice. The potential side effects of 2-ME on SCID mice were also investigated. Methods: Severe combined immune deficient mice were injected with HEC-1-A cells (1 × 10 6/mouse) and a 18 day administration of 2-ME was followed after 1 week cell implantation. Tumor volume, weight, body weight and blood chemistry were determined. Tumor tissues were examined with an antibody against the proliferative cell nuclear antigen (PCNA) and Ki-67. Liver, spleen, kidney, heart, lung and uterus were screened by pathological examinations. Results: 2-ME (100 mg/kg p.o.) did not inhibit the growth of human endometrial carcinoma as compared to control. Necrotic areas were similar in both 2-ME-treated and -untreated tumor tissues. The expressions of PCNA and Ki-67 were similar in 2-ME-treated and untreated tumor sections. The wet weight of uterus was increased to more than threefold. The epithelial cells and glands in endometrium were increased. No significant difference was detected in blood AST, ALT and BUN. Conclusions: 2-ME has no antitumor effects on human endometrial carcinoma in our animal model. Its proliferative effects on endometrium and uterus might limit its use in gynecological cancers.
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| 4. |
- Li, Nannan, et al.
(författare)
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Phytolith and simulation evidence for precipitation-modulated vegetation dynamics along the East Asian monsoon margin
- 2022
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182. ; 590
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Tidskriftsartikel (refereegranskat)abstract
- An improved understanding of past interactions between terrestrial vegetation and various forcings, such as climate change, human impact, and paleofire, is crucial for assessing impacts of future global change on terrestrial ecosystems. This study seeks to find the key factor or factors that have driven Holocene vegetation change along the East Asian monsoon margin. Several high-resolution pollen records are reviewed and new phytolith-based paleovegetation reconstructions and physical geochemical datasets are presented from a peatland in northeastern China. Using 108 modern topsoil samples as a training set, canopy cover and vegetation composition are estimated for the period since 5100 cal. yr BP. Variation partitioning analysis (VPA) is used to determine the relative importance of climate change, human impacts, and paleofire disturbance. The generalized dynamic vegetation model LPJ-GUESS is forced with climate anomaly output from an atmospheric general circulation model to simulate vegetation dynamics during the mid-Holocene and the pre-industrial era. The proxy-based estimates are compared to modelling output. Results indicate that regional tree cover varied from 10% to 40% during the past five millennia. The single-core, phytolith-based reconstructions are generally consistent with stacked tree pollen z-scores calculated from different records along the East Asian monsoon margin, implying that mid-Holocene tree cover decrease was persistent and almost synchronous over extensive areas. VPA demonstrates that long-term monsoon marginal vegetation successions were mainly caused by climate effects. Numerical modelling suggests that since the mid-Holocene the retreat of forests along the monsoon margin was primarily associated with precipitation deficits. Our investigation highlights that the precipitation associated with the East Asian monsoon system has exerted a stronger influence than the westerlies on the monsoon margin climate and vegetation change. With ongoing global change, close attention to variations in precipitation patterns and amounts should be especially helpful in efforts aimed at ecological monitoring, change prediction, and restoration.
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| 5. |
- Lin, Yuanbao, et al.
(författare)
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One-Step Blade-Coated Highly Efficient Nonfullerene Organic Solar Cells with a Self-Assembled Interfacial Layer Enabled by Solvent Vapor Annealing
- 2019
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Ingår i: Solar RRL. - : Wiley. - 2367-198X. ; 3:8
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Tidskriftsartikel (refereegranskat)abstract
- A pronounced enhancement of the power conversion efficiency (PCE) by 38% is achieved in one-step doctor-blade printing organic solar cells (OSCs) via a simple solvent vapor annealing (SVA) step. The organic blend composed of a donor polymer, a nonfullerene acceptor, and an interfacial layer (IL) molecular component is found to phase-separate vertically when exposed to a solvent vapor-saturated atmosphere. Remarkably, the spontaneous formation of a fine, self-organized IL between the bulk heterojunction (BHJ) layer and the indium tin oxide (ITO) electrode facilitated by SVA yields solar cells with a significantly higher PCE (11.14%) than in control devices (8.05%) without SVA and in devices (10.06%) made with the more complex two-step doctor-blade printing method. The stratified nature of the ITO/IL/BHJ/cathode is corroborated by a range of complementary characterization techniques including surface energy, cross-sectional scanning electron microscopy, grazing incidence wide angle X-ray scattering, and X-ray photoelectron spectroscopy. This study demonstrates that a spontaneously formed IL with SVA treatment combines simplicity and precision with high device performance, thus making it attractive for large-area manufacturing of next-generation OSCs.
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| 6. |
- Liu, Alei, et al.
(författare)
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Manipulate Micrometer Surface and Nanometer Bulk Phase Separation Structures in the Active Layer of Organic Solar Cells via Synergy of Ultrasonic and High-Pressure Gas Spraying
- 2019
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 11:11, s. 10777-10784
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Tidskriftsartikel (refereegranskat)abstract
- For organic solar cells, the vertical and lateral micro-/nanometer-scale structure in the active layer largely determines the device performance. In this work, the surface and bulk domain size of the photoactive layer are successfully manipulated with a facile two-step spraying method, that is, an ultrathin active layer by high-pressure spraying is deliberately stacked on top of the thick active layer by ultrasonic spraying. Thus, the morphology is effectively optimized with the comprehensive study of optical and electrical characteristics, such as photon absorption, exciton dissociation efficiency, and bimolecular recombination. Moreover, the novel method can be used not only in the fullerene system but also in the nonfullerene system, demonstrating the remarkable universality through this synergy method. This work provides an easy and reliable strategy to improve photovoltaic device performance in the industrial large-area spray-coating process.
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| 7. |
- Yang, Junyu, et al.
(författare)
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Roll-to-Roll Slot-Die-Printed Polymer Solar Cells by Self-Assembly
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:26, s. 22485-22494
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Tidskriftsartikel (refereegranskat)abstract
- Extremely simplified one-step roll-to-roll slot-die-printed flexible indium tin oxide (ITO)-free polymer solar cells (PSCs) are demonstrated based on the ternary blends of electron-donor polymer thieno[3,4-b]thiophene/benzodithiophene, electron-acceptor fullerene [6,6]-phenyl-C-71-butyric acid methyl ester, and electron-extracting polymer poly[(9,9-bis(3-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) at room temperature (RT) in ambient air. The flexible ITO-free PSC exhibits a comparable power conversion efficiency (PCE) with the device employing complicated two-step slot-die printing (5.29% vs 5.41%), which indicates that PFN molecules can migrate from the ternary nanocomposite toward the Ag cathode via vertical self-assembly during the one-step slot-die printing process in air. To confirm the migration of PFN, the morphology and elemental analysis as well as charge transport of different active layers are investigated by the in situ transient film drying process, transmission electron microscopy, atomic force microscopy, contact angle and surface energy, X-ray photoelectron spectroscopy, scanning electron microscopy, impedance spectroscopy, transient photovoltage and transient photocurrent, and laser-beam-induced current. Moreover, the good air and mechanical stability of the flexible device with a decent PCE achieved in 1 cm(2) PSCs at RT in air suggests the feasibility of energy-saving and time-saving one-step slot-die printing to large-scale roll-to-roll manufacture in the future.
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| 8. |
- Yu, Hongling, 1987-
(författare)
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Color Tuning for Perovskite Light-Emitting Diodes
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metal halide perovskites (MHPs) are recognized as promising semiconductor materials for a variety of optical and electrical device applications due to their cost-effective and outstanding optoelectronic properties. As one of the most significant applications, perovskite light-emitting diodes (PeLEDs) hold promise for future lighting and display technologies, attributed to their high photoluminescence quantum yield (PLQY), high color purity, and tunable emission color. The emission colors of PeLEDs can be tuned by mixing the halide anions, adjusting the size of perovskite nanocrystals, or changing the dimensionality of perovskites. However, in practice, all these different approaches have their own advantages and challenges. This thesis centres around the color tunability of perovskites, aiming to develop PeLEDs with different colors using different approaches.We first demonstrate red and near-infrared PeLEDs using a straightforward approach – in situ solution-processed perovskite quantum dots (PQDs). PQDs prepared from colloidal approaches are widely reported and used in LEDs. In contrast, PQDs prepared from the in situ approaches are hardly reported, although they have advantages for device applications. By employing aromatic ammonium iodide (1-naphthylmethyl ammonium iodide, NMAI) as an agent into perovskite precursor solutions, together with annealing temperature modulation, we obtain in situ grown PQDs delivering high external quantum efficiencies (EQEs) of up to 11.0% with tunable electroluminescence (EL) spectra (667 - 790 nm). Our in situ generated PQDs based on pure-halogen perovskites can be easily obtained through a simple deposition process and free of phase segregation, making them a more promising approach for tuning the emission colors of perovskite LEDs.We then move to blue PeLEDs using cesium-based mixed-Br/Cl perovskites. Although mixed halides are a straightforward strategy to tune the emission color, PeLEDs based on this approach suffer from poor color stability, which is attributed to surface defects at grain boundaries. Under the condition of optical excitations, light density over a certain value (a threshold), oxygen, and surface defects at perovskite grain boundaries are found to be key factors inducing photoluminescence (PL) spectral instability of CsPb(Br1−xClx)3 perovskites. Upon electrical bias, defects at grain boundaries provide undesirable halide migration channels, responsible for EL spectral instability issues. Through effective defect passivation, the PL spectral resistance to oxygen is enhanced; moreover, high-performance and color-stable blue PeLEDs are achieved, delivering a maximum luminance of 5351 cd m–2 and a peak EQE of 4.55% with a peak emission wavelength at 489 nm. These findings provide new insights into the color instability issue of mixed halide blue perovskites, against which we also demonstrate an effective strategy.We finally realize single-emissive-layer (EML) white PeLEDs by employing a mixed halide perovskite film as the EML. In spite of high-performance monochromatic blue, green, and red colors, the development of white PeLEDs, especially for single-EML ones, remains a very big challenge. By effective modulation of the halide salt precursors, we achieve single-EML white PeLEDs with Commission Internationale de L’Eclairage (CIE) coordinates of (0.33, 0.33), close to those (0.3128, 0.3290) of the CIE standard illuminant D65. This work not only provides a successful demonstration of a single-EML white PeLED, but also provides useful guidelines for the future development of highperformance single-EML white PeLEDs.
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