| 1. |
- Cai, Bin, et al.
(författare)
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Boosting the power conversion efficiency of perovskite solar cells to 17.7% with an indolo[3,2-b]carbazole dopant-free hole transporting material by improving its spatial configuration
- 2019
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 7:24, s. 14835-14841
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Tidskriftsartikel (refereegranskat)abstract
- The development of facilely synthesized, dopant-free hole-transporting materials (HTMs) with high efficiency is of great significance for the potential application of perovskite solar cells (PSCs). Herein, we report two novel indolo[3,2-b]carbazole (ICZ) based small molecules obtained via a three-step reaction in a high yield without using expensive catalysts, namely C201 and C202, and further apply them as dopant-free HTMs in PSCs. Compared with C201, C202 contains two additional biphenylamino groups to improve its spatial configuration. It is found that the interplay between the molecular geometry and the aggregation behavior can exert a great influence on the film formation property and thus on the device performance. Strikingly, the champion devices employing C202 as the HTM deliver a much higher PCE of up to 17.7%, which is substantially higher than that of devices containing C201 (8.7%) under 100 mW cm(-2) illumination (AM 1.5G). It is revealed that the C202 capping layer exhibits a more homogeneous and uniform surface morphology as compared to that of C201, which effectively reduces the charge recombination losses and facilitates charge extraction, leading to a much-enhanced photovoltaic performance. This is the first example of ICZ core-based small molecules as dopant-free HTMs in PSCs. Moreover, the PSCs containing C202 as the HTM also exhibited good long-term stability under ambient conditions (40% RH) as compared to devices with doped spiro-OMeTAD, due largely to the hydrophobic nature of C202 which prevented moisture from destroying the perovskite film. This work offers a new avenue for developing cost-effective and stable HTMs for PSCs and other optoelectronic devices.
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| 2. |
- Han, Siyuan, et al.
(författare)
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Side-chain engineering of PEDOT derivatives as dopant-free hole-transporting materials for efficient and stable n-i-p structured perovskite solar cells
- 2020
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 8:27, s. 9236-9242
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Tidskriftsartikel (refereegranskat)abstract
- Low-cost poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have been widely used as hole-transporting materials (HTMs) in p-i-n perovskite solar cells (PSCs). However, reports on the use of PEDOT-based HTMs in regular PSCs have been rather limited up till now due to the low solubility of PEDOT in organic solvents. In this work, we report three PEDOT derivatives, namely, PEDOT-C6 (P6), PEDOT-C10 (P10), and PEDOT-C14 (P14), with a simple synthetic process by tailoring the length of the alkyl side-chains, and apply them as dopant-free HTMs in mesoscopic n-i-p structured PSCs. It is revealed that the alkyl side-chain length has a significant impact on the film morphology, hole transport capability, and thus the overall solar cell performance. The devices with P10 afford a champion PCE of 16.2% at one sun illumination (100 mW cm(-2), AM 1.5G), which is significantly higher compared to those based on P6 (12.1%) and P14 (14.8%) under identical conditions. This has been the highest PCE reported so far for dopant-free PEDOT-based HTMs in conventional PSCs. The greatly enhanced photovoltaic performance observed for the P10-based devices is mainly attributed to the superior film formation property and hole transport capability of P10. Furthermore, the devices utilizing P10 also show excellent ambient stability, retaining 75% of their initial performance at a relative humidity (RH) of 80% after 120 h due to the high moisture resistivity of the HTM. The present work provides a new avenue for further developing low-cost, efficient, and stable HTMs in PSCs in the future.
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| 3. |
- Jiang, Xiaoqing, et al.
(författare)
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A solution-processable copper(II) phthalocyanine derivative as a dopant-free hole-transporting material for efficient and stable carbon counter electrode-based perovskite solar cells
- 2017
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 5:34, s. 17862-17866
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Tidskriftsartikel (refereegranskat)abstract
- A solution-processable copper(II) phthalocyanine derivative coded as CuPc-TIPS has been synthesized and adopted as a hole-transporting material (HTM) in perovskite solar cells (PSCs), in combination with a mixed-ion perovskite absorber and a low-cost carbon cathode. Optimised PSC devices based on pristine CuPc-TIPS without any additives or dopants show a decent power conversion efficiency of 14.0% (measured at 100 mW cm(-2) illumination, AM 1.5G), together with a good long-termstability under ambient conditions. The present finding highlights the potential of solution-processed copper phthalocyanine derivative-based HTMs for the development of efficient and stable PSCs in the future.
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| 4. |
- Jiang, Xiaoqing, et al.
(författare)
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Efficient perovskite solar cells employing a solution-processable copper phthalocyanine as a hole-transporting material
- 2017
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Ingår i: Science China Chemistry. - : Science in China Press. - 1674-7291 .- 1869-1870. ; 60:3, s. 423-430
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Tidskriftsartikel (refereegranskat)abstract
- The development of alternative low-cost and high-performing hole-transporting materials (HTMs) is of great significance for the potential large-scale application of perovskite solar cells (PSCs) in the future. Here, a facilely synthesized solution-processable copper tetra-(2,4-dimethyl-3-pentoxy) phthalocyanine (CuPc-DMP) via only two simple steps, has been incorporated as a hole-transporting material (HTM) in mesoscopic perovskite solar cells (PSCs). The optimized devices based on such a HTM afford a very competitive power conversion efficiency (PCE) of up to 17.1% measured at 100 mW cm(-2) AM 1.5G irradiation, which is on par with that of the well-known 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) (16.7%) under equivalent conditions. This is, to the best of our knowledge, the highest value reported so far for metal organic complex-based HTMs in PSCs. The advantages of this HTM observed, such as facile synthetic procedure, superior hole transport characteristic, high photovoltaic performance together with the feasibility of tailoring the molecular structure would make solution-processable copper phthalocyanines as a class of promising HTM that can be further explored in PSCs. The present finding highlights the potential application of solution processed metal organic complexes as HTMs for cost-effective and high-performing PSCs.
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| 5. |
- Jiang, Xiaoqing, et al.
(författare)
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High-Performance Regular Perovskite Solar Cells Employing Low-Cost Poly(ethylenedioxythiophene) as a Hole-Transporting Material
- 2017
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we successfully applied a facile in-situ solid-state synthesis of conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) as a HTM, directly on top of the perovskite layer, in conventional mesoscopic perovskite solar cells (PSCs) (n-i-p structure). The fabrication of the PEDOT film only involved a very simple in-situ solid-state polymerisation step from a monomer 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) made from a commercially available and cheap starting material. The ultraviolet photoelectron spectroscopy (UPS) demonstrated that the as-prepared PEDOT film possesses the highest occupied molecular orbital (HOMO) energy level of -5.5 eV, which facilitates an effective hole extraction from the perovskite absorber as confirmed by the photoluminescence measurements. Optimised PSC devices employing this polymeric HTM in combination with a low-cost vacuum-free carbon cathode (replacing the gold), show an excellent power conversion efficiency (PCE) of 17.0% measured at 100 mW cm(-2) illumination (AM 1.5G), with an open-circuit voltage (V-oc) of 1.05 V, a short-circuit current density (J(sc)) of 23.5 mA/cm(2) and a fill factor (FF) of 0.69, respectively. The present finding highlights the potential application of PEDOT made from solid-state polymerisation as a HTM for cost-effective and highly efficient PSCs.
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| 6. |
- Jiang, Xiangang, et al.
(författare)
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Internal erosion of debris-flow deposits triggered by seepage
- 2023
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Ingår i: Engineering Geology. - : Elsevier BV. - 0013-7952 .- 1872-6917. ; 314, s. 107015-
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Tidskriftsartikel (refereegranskat)abstract
- Debris flows can be triggered by runoffs at considerably steep natural channels and streams. Specifically, runoffgenerated debris-flow deposits are loose mixtures, comprising coarse and fine particles. Owing to seeping water, these fine particles are eroded and transported through the skeleton formed by the coarse particles. Such erosion can modify the porosity of deposits and influence their mechanical characteristics, which can be non-negligible for geotechnical and geological engineering. In this study, seven groups of seepage tests on gravel-sand-clay mixtures with different coarse particle content proportions (48%, 52%, 60%, 70%, 80%, 90%, and 100%) were conducted to investigate the erosion characteristics of debris-flow deposits triggered by seepage flows. In particular, concentrated leak erosion, internal instability erosion, and piping were noted in the soil with a coarse particle content of 48%-80%. Further, when the coarse particle content exceeds 80%, the soil does not disintegrate. A model coupling seepage and internal erosion was also developed to characterise internal erosion. For this model, mass conservation equations were reformulated for different types of internal erosion, based on the assumptions for the pore channel erosion of suspended materials and general erosion. Moreover, an equation based on the internal erosion rate, considering the pore size distribution and hydraulic gradient, was firstly introduced for concentrated leak and internal instability erosion. This equation could efficiently evaluate the mass of particles eroded from the soil. Lastly, the model was calibrated based on experimental data; the corresponding results are discussed herein.
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| 7. |
- Jiang, Xiaoqing, et al.
(författare)
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Molecular Engineering of Copper Phthalocyanines : A Strategy in Developing Dopant-Free Hole-Transporting Materials for Efficient and Ambient-Stable Perovskite Solar Cells
- 2019
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Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Copper (II) phthalocyanines (CuPcs) have attracted growing interest as promising hole-transporting materials (HTMs) in perovskite solar cells (PSCs) due to their low-cost and excellent stability. However, the most efficient PSCs using CuPc-based HTMs reported thus far still rely on hygroscopic p-type dopants, which notoriously deteriorate device stability. Herein, two new CuPc derivatives are designed, namely CuPc-Bu and CuPc-OBu, by molecular engineering of the non-peripheral substituents of the Pc rings, and applied as dopant-free HTMs in PSCs. Remarkably, a small structural change from butyl groups to butoxy groups in the substituents of the Pc rings significantly influences the molecular ordering and effectively improves the hole mobility and solar cell performance. As a consequence, PSCs based on dopant-free CuPc-OBu as HTMs deliver an impressive power conversion efficiency (PCE) of up to 17.6% under one sun illumination, which is considerably higher than that of devices with CuPc-Bu (14.3%). Moreover, PSCs containing dopant-free CuPc-OBu HTMs show a markedly improved ambient stability when stored without encapsulation under ambient conditions with a relative humidity of 85% compared to devices containing doped Spiro-OMeTAD. This work thus provides a fundamental strategy for the future design of cost-effective and stable HTMs for PSCs and other optoelectronic devices.
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| 8. |
- Qu, Jishuang, et al.
(författare)
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Improved performance and air stability of perovskite solar cells based on low-cost organic hole-transporting material X60 by incorporating its dicationic salt
- 2018
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Ingår i: Science in China Series B. - : Science Press. - 1674-7291 .- 1869-1870. ; 61:2, s. 172-179
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Tidskriftsartikel (refereegranskat)abstract
- The development of an efficient, stable, and low-cost hole-transporting material (HTM) is of great significance for perovskite solar cells (PSCs) from future commercialization point of view. Herein, we specifically synthesize a dicationic salt of X60 termed X60(TFSI)(2), and adopt it as an effective and stable "doping" agent to replace the previously used lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) for the low-cost organic HTM X60 in PSCs. The incorporation of this dicationic salt significantly increases the hole conductivity of X60 by two orders of magnitude from 10(-6) to 10(-4) S cm(-1). The dramatic enhancement of the conductivity leads to an impressive power conversion efficiency (PCE) of 19.0% measured at 1 sun illumination (100 mW cm(-2), AM 1.5 G), which is comparable to that of the device doped with LiTFSI (19.3%) under an identical condition. More strikingly, by replacing LiTFSI, the PSC devices incorporating X60(TFSI)(2) also show an excellent long-term durability under ambient atmosphere for 30 days, mainly due to the hydrophobic nature of the X60(TFSI)(2) doped HTM layer, which can effectively prevent the moisture destroying the perovskite layer. The present work paves the way for the development of highly efficient, stable, and low-cost HTM for potential commercialization of PSCs.
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| 9. |
- Wei, Daixiu, et al.
(författare)
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Development of strong and ductile metastable face-centered cubic single-phase high-entropy alloys
- 2019
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Ingår i: Acta Materialia. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1359-6454 .- 1873-2453. ; 181, s. 318-330
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Tidskriftsartikel (refereegranskat)abstract
- Face-centered cubic (fcc)-phase high-entropy alloys (HEAs) have attracted much academic interest, with the stacking fault energy (SFE) playing an important role in regulating their mechanical behaviors. Here, we revealed the principles for regulating both the elastic and plastic behaviors by composition modification and Mo addition in an fcc-phase quaternary CoCrFeNi system with the assistance of ab initio and thermodynamics calculations. An increase in Co content and a decrease in Fe and Ni contents reduced the fcc phase stability and SFE, but enhanced the elastic modulus, anisotropy, and lattice friction stress. A minor substitution of Co by Mo increased the lattice constant, but decreased the SFE and elastic modulus. Based on these findings, we developed a series of strong and ductile metastable fcc-phase CoxCr25(FeNi)(70-x)Mo-5 (x = 30, 40, 50) HEAs with mechanical properties superior to those of the CoCrFeNi HEM. The careful investigation revealed that the enhanced mechanical properties are due to the Mo-addition-induced strengthening accompanied with a low-SFE-induced restriction of planar behavior of dislocations, mechanical twinning, and strain-induced martensitic transformation. The findings shed light on the development of high-performance HEAs.
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| 10. |
- Wei, D., et al.
(författare)
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Novel Co-rich high performance twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) high-entropy alloys
- 2019
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Ingår i: Scripta Materialia. - : Acta Materialia Inc. - 1359-6462 .- 1872-8456. ; 165, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- The equiatomic CoCrMnNiFe high-entropy alloy (HEA) has attracted much attention owing to its exceptional mechanical properties. Here, we designed novel face-centered cubic (fcc) phase Co-rich non-equiatomic CoCrMnNiFe HEAs with tensile properties superior to the counterparts, derived from lowering stacking fault energy (SFE) via modifying constituent concentrations. The decrease of Mn, Ni, Fe meanwhile increase of Co, Cr concentrations does reduce the SFE value, based on ab initio and thermodynamics calculations. Hereinto, Co 35 Cr 20 Mn 15 Ni 15 Fe 15 and Co 35 Cr 25 Mn 15 Ni 15 Fe 10 HEAs overcame the strength-ductility trade-off, contributing to twinning-induced plasticity (TWIP) or transformation-induced plasticity (TRIP) effects, respectively. The present study sheds light on developing high performance HEAs.
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