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Effect of Electron-Acceptor Content on the Efficiency of Regioregular Double-Cable Thiophene Copolymers in Single-Material Organic Solar Cells
摘要： Three regioregular thiophenic copolymers, characterized by a bromine atom or a C60-fullerene group at different molar ratios at the end of a decamethylenic plastifying side chain, have been successfully synthesized using a straightforward postpolymerization functionalization procedure based on a Grignard coupling reaction. Owing to their good solubility in common organic solvents, the products were fully characterized using chromatographic, spectroscopic, thermal, and morphological techniques and used as single materials in the photoactive layers of organic solar cells. The photoconversion efficiencies obtained with copolymers were compared with those of a reference cell prepared using a physical blend of the precursor homopolymer and [6,6]-phenyl-C61-butyric acid methyl ester. The best results were obtained with COP2, the copolymer with a 21% molar content of C60-functionalized side chains. The use of the double-cable polymer made possible an enhanced control on the nanomorphology of the active blend, thus reducing phase-segregation phenomena as well as the macroscale separation between the electron-acceptor and -donor components, yielding a power conversion efficiency higher than that of the reference cell (4.05 vs 3.68%). Moreover, the presence of the halogen group was exploited for the photo-cross-linking of the active layer immediately after the thermal annealing procedure. The cross-linked samples showed an increased stability over time, leading to good efficiencies even after 120 h of accelerated aging: this was a key feature for the widespread practical applicability of the prepared devices.
关键词： photo-cross-linking,C60-fullerene,double-cable polymer,thermal annealing,regioregular thiophenic copolymers,Grignard coupling reaction,organic solar cells,photoconversion efficiencies
更新于2025-09-11 14:15:04
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High-Performance Ternary Organic Solar Cells Enabled by Combining Fullerene and Nonfullerene Electron Acceptors
摘要： Recently, by elaborately designing nonfullerene acceptors and selecting suitable polymer donors great progresses have been made towards binary organic solar cells (OSCs) with power conversion efficiencies (PCEs) over 15%. Ternary organic photovoltaics by introducing a third component into the host binary system is recognized to be highly effective to elevate the performance through extending the light absorption, manipulating the recombination behavior of the carriers, and improving the morphology of the active layer. In this work, we synthesized a new electron-acceptor ZITI-4F matching it with the wide-bandgap polymer donor PBDB-T The PBDB-T:ZITI-4F-based OSC showed a high PCE of 12.33%. After introducing 40% of PC71BM as the third component, the ternary device achieved an improved PCE of 13.40% with simultaneously improved photovoltaic parameters. The higher performance of the ternary device can be attributed to the improved and more balanced charge mobility, reduced bimolecular recombination, and more favorable morphology. These results indicate that the cooperation of a fullerene-based acceptor and a nonfullerene acceptor to fabricate ternary OSCs is an effective approach to optimizing morphology and therefore to increase the performance of OSCs.
关键词： ternary organic solar cells,power conversion efficiencies,indenoin-dene,electron acceptors
更新于2025-09-11 14:15:04
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Modulation of Three p-Type Polymers Containing a Fluorinated-Thiophene-Fused-Benzotriazole Unit To Pair with a Benzotriazole-Based Non-fullerene Acceptor for High <i>V</i> <sub/>OC</sub> Organic Solar Cells
摘要： Three 6-?uoro-thieno[2′,3′:4,5]benzo[1,2-d][1,2,3]triazole (fBTAZT) containing copolymers, named as PfBTAZT-H, PfBTAZT-F, and PfBTAZT-Cl, were employed to pair with a benzo[1,2-d][1,2,3]triazole (BTA) based non-fullerene acceptor BTA3 for the applicaition in organic solar cells (OSCs). By introducing ?uorine or chlorine atoms into the thiophene side chains on BDT units, the highest occupied molecular orbital (HOMO) energy levels of polymers shift down in sequence, and PfBTAZT-Cl shows an obvious blue-shift of absorption spectrum. PfBTAZT-F:BTA3-based OSC attains a VOC of 1.05 V, a JSC of 11.83 mA cm?2, and FF of 0.62, leading to a PCE of 7.69%, which are higher than that of PfBTAZT-H:BTA3 (VOC = 0.99 V, JSC = 11.60 mA cm?2, FF = 0.58, and PCE = 6.65%) due to its well-matched HOMO energy level, higher charge mobilities, and favorable ?lm morphology. More surprisingly, chlorinated polymer PfBTAZT-Cl obtains the highest VOC of 1.20 V and PCE of 8.00%, which is attributed to the lowest HOMO energy level, largely decreased voltage loss (ΔVloss = 0.56 V compared to 0.77 V for PfBTAZT-H:BTA3 0.71 V for PfBTAZT-F:BTA3), more complementary absorption with that of BTA3, and e?ective charge generation. Our results demonstrate that chlorination is an e?ective approach to realize a high PCE and VOC and thiophene-fused benzotriazole (BTAZT) based polymers are also good candidates for material combinations in “Same-A-Strategy” (SAS).
关键词： fluorinated-thiophene-fused-benzotriazole,PCE,non-fullerene acceptor,organic solar cells,high VOC,benzotriazole-based
更新于2025-09-11 14:15:04
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Introducing Four 1,1-Dicyanomethylene-3-Indanone (IC) End-capped Groups as an Alternative Strategy for the Design of Small Molecular Nonfullerene Acceptors
摘要： Linear A-D-A or A-π-D-π-A architectures are predominant in the design of promising non-fullerene acceptors (NFAs), which promoted the rapid progress of organic solar cells (OSCs). However, utilization of four electron-accepting units (A) to construct four-armed NFAs is rarely reported and the relationship of structure-properties-performance is unclear. In this study, we designed and synthesized a novel acceptor (A401) with (AA)-π-D-π-(AA) configuration, where four 1,1-dicyanomethylene-3-indanone (IC) groups were used as the end-capped segments. When A401 was paired with a classic p-type polymer PBDB-T, a power conversion efficiency (PCE) of 7.54% could be achieved, which was much higher than that of the reported two-armed analogue of DC-IDT2T (3.93%). The improved photovoltaic performance of A401 should be ascribed to the high electron-affinity. Our results indicate introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFAs. Our conceptualized molecular architecture will encourage further research of high-performance multi-armed NFAs.
关键词： photovoltaic performance,electron-affinity,electron-accepting units,organic solar cells,non-fullerene acceptors
更新于2025-09-10 09:29:36
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Solar glasses' provide power for devices
摘要： The dark lenses of sunglasses have been replaced with organic solar cells by scientists in Germany. The cells can power a small microcontroller that sends information on ambient conditions to displays in the spectacle arms, and in future might provide power for personal devices such as hearing aids.
关键词： power for devices,organic solar cells,solar glasses
更新于2025-09-09 09:28:46
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Modeling of degradation in normal and inverted OSC devices
摘要： Degradation of organic solar cells (OSC) remains a problem which has prevented its commercial exploitation. While there are several experimental studies pointing towards different reasons behind the atmospheric degradation of these devices, yet a microscopic understanding is lacking. Here, we present a combined experimental and modeling study to understand the degradation in the electrical characteristics of OSC in normal and inverted architectures, further correlated with the interfacial degradation. Our investigations show that degradation of current density – voltage (J-V) characteristics of normal devices is extremely fast i.e. 50% in 9 h as against 21 days for inverted devices. Interestingly, degradation in normal devices is driven primarily by a decrease in short circuit current density (Jsc) without appearance of S-shape in J-V characteristics while degraded inverted devices exhibit S-shaped J-V characteristics. Modeling of J-V data along with time dependent capacitance-voltage (C-V) analysis suggests that the degradation in normal OSC devices can be modeled using degradation induced reduced effective area theory supporting the formation of Al2O3 pockets at the cathode-active layer interface which grow exponentially with storage time eventually forming a continuous layer. In contrast, inverted devices degrade much slowly, via deterioration of hole transporting MoO3 layer resulting in increased anode barrier height and reduced surface recombination velocity (Sp) at anode causing a S shaped J-V curve due to decreased carrier extraction rate. The study clearly highlights the differences between the way two differences architectures and elucidates the underlying reasons.
关键词： Drift diffusion,Degradation,Organic solar cells,Modeling
更新于2025-09-09 09:28:46
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End-cap Group Engineering of a Small Molecule Non-Fullerene Acceptor: The Influence of Benzothiophene Dioxide
摘要： In this study, a sulfonyl-containing end-capping moiety, benzothiophene dioxide, was selected to prepare the nonfullerene acceptor ITBC. ITBC has an acceptor?donor?acceptor (A-D-A) structure, with indacenodithieno[3,2-b]thiophene (IDTT) as the electron-rich core moiety. The strong electron-withdrawing sulfonyl acceptor units leads to extended UV?vis absorption into the near-IR region and relatively low frontier molecular orbital energy levels (LUMO/HOMO: ?4.13 eV/?5.61 eV) with a narrow bandgap of 1.48 eV. These values compare favorably to the well-studied small molecule acceptor 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile end-capped indacenodithieno[3,2-b]thiophene (ITIC). A power conversion e?ciency of 4.17% was achieved by fabricating organic solar cells with the ?uorinated conjugated polymer FTAZ as the donor and ITBC as the acceptor. These results indicate that benzothiophene dioxide is a novel electron-withdrawing end-capping unit for ITBC, and can be used as an electron acceptor for organic solar cells.
关键词： fused conjugated system,non-fullerene acceptor,e?cient photovoltaics,benzothiophene dioxide,organic solar cells
更新于2025-09-04 15:30:14