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Quantification of Photophysical Processes in Alla??Polymer Bulk Heterojunction Solar Cells
摘要： Combined data of transient optical and electro-optical experiments reveals the efficiency-determining processes in all-polymer solar cells and allows precisely quantifying their yields. For the test system presented here, field-dependent charge separation is shown to limit the fill factor and thus the performance by comparing the experimentally-measured current-voltage characteristics to those reproduced by drift-diffusion simulations using the spectroscopically-determined kinetic parameters.
关键词： all-polymer solar cells,bulk heterojunction,non-fullerene acceptors,transient absorption,organic photovoltaics
更新于2025-09-23 15:19:57
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Significantly Enhanced Molecular Stacking in Ternary Bulk Heterojunctions Enabled by an Appropriate Side Group on Donor Polymer
摘要： Ternary strategy is a promising approach to broaden the photoresponse of polymer solar cells (PSCs) by adopting combinatory photoactive blends. However, it could lead to a more complicated situation in manipulating the bulk morphology. Achieving an ideal morphology that enhances the charge transport and light absorption simultaneously is an essential avenue to promote the device performance. Herein, two polymers with different lengths of side groups (P1 is based on phenyl side group and P2 is based on biphenyl side group) are adopted in the dual-acceptor ternary systems to evaluate the relationship between conjugated side group and crystalline behavior in the ternary system. The P1 ternary system delivers a greatly improved power conversion efficiency (PCE) of 13.06%, which could be attributed to the intense and broad photoresponse and improved charge transport originating from the improved crystallinity. Inversely, the P2 ternary device only exhibits a poor PCE of 8.97%, where the decreased device performance could mainly be ascribed to the disturbed molecular stacking of the components originating from the overlong conjugated side group. The results demonstrate a conjugated side group could greatly determine the device performance by tuning the crystallinity of components in ternary systems.
关键词： ternary systems,ternary bulk heterojunctions,complementary absorption,polymer solar cells,molecular stacking,side chain effect
更新于2025-09-23 15:19:57
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Efficient Polymer Solar Cells Employing Solutiona??Processed Conjugated Polyelectrolytes with Differently Charged Side Chains
摘要： Poly(6-(4,7-dimethyl-2H-benzo[d][1,2,3]triazol-2-yl)-N,N,N-trimethylhexan-1 aminium iodide) (PBTz-TMAI) and poly(sodium 4-(4,7-dimethyl-2H-benzo[d][1,2,3]triazol-2-yl)butane-1-sulfonate) (PBTz-SO3Na) based on the same benzotriazole-conjugated backbone but with ammonium and sulfonated side chains are designed and synthesized through side-chain functionalization and Yamamoto polymerization, respectively, and are used as the cathode interlayers in fullerene- and non-fullerene-based polymer solar cells. The interfacial modification of PBTz-TMAI and PBTz-SO3Na onto the active layer achieves good energy alignment at cathode electrodes and optimized exciton-dissociation efficiency from the active layer. Consequently, the power conversion efficiencies (PCEs) of 7.8% and 9.6% are obtained for the fullerene PTB7:PC71BM-based and non-fullerene PBDB-T:ITIC-based polymer solar cells (PSCs) with PBTz-SO3Na interlayer. The PCS devices based on PTB7:PC71BM and PBDB-T:ITIC active layers with PBTz-TMAI interlayer achieved a remarkably improved performance with PCEs of 8.2% and 10.2%, respectively.
关键词： cathode interlayers,polymer solar cells,conjugated polyelectrolytes
更新于2025-09-23 15:19:57
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Effect of colloid aggregation characteristic on ZnO interface layer and photovoltaic performance of polymer solar cells
摘要： ZnO as a classical n-type semiconductor oxide is widely used as the electron transport layer for high-efficiency polymer solar cells by using solution processing. To study the effect of ZnO colloid aggregation size on the morphology of ZnO interface layer and photovoltaic performance of polymer solar cells. The ZnO colloid aggregation size was adjusted by aging time, and the PTB7-Th:PC71BM solar cells with various ZnO interface layers were fabricated. The results showed that morphology, structure and property of ZnO interface layer were depended on the ZnO colloid particle size, and then determined the photoelectric performance of the PTB7-Th:PC71BM solar cell. The best performance of PTB7-Th:PC71BM solar cell with 10.21% was obtained when the ZnO precursor solution was set at 2 h aging. The ZnO interface layer with good morphology and appropriate energy level improved the mobility and lifetime of charge carrier. Moreover, it also attributed good interface contact between the ZnO layer and the PTB7-Th:PC71BM active layer, which enhanced the electron transfer and reduced the charge recombination at the interface.
关键词： ZnO colloidal particle size,ZnO interface layer,Polymer solar cells,Aging time,Photovoltaic performance
更新于2025-09-23 15:19:57
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a??Double-Acceptor-Typea?? Random Conjugated Terpolymer Donors for Additive-Free Non-Fullerene Organic Solar Cells
摘要： Random conjugated terpolymers (RCTs) not only promote great comprehension and realization for state-of-the-art high effective non-fullerene polymer solar cells (OSCs) but also offer a simple and practical synthetic strategy. However, the photovoltaic properties of RCTs yet lagged behind that of the donor-acceptor alternating copolymer, especially in the additive-free devices. Hence, we developed two feasible “double acceptor type” random conjugated terpolymers, PBDB-TAZ20 and PBDB-TAZ40. The additive-free OSCs based on PBDB-TAZ20:ITIC and PBDB-TAZ40:ITIC exhibit decent efficiencies of 12.34% and 11.27%, respectively, which both surpass the PBDB-T:ITIC-based device. For the RCTs, the reasonably weakened crystallinity and reduced phase separation degree are demonstrated to help improve charge transport, reduce bimolecular recombination and thus enhance the photovoltaic performance of the additive-free OSCs. The results imply that adding a third moiety into the D-A polymer donors provides a simple but efficient synthetic approach for high-performance OSCs.
关键词： polymer solar cells,crystallinity,non-fullerenes,morphology,random terpolymers
更新于2025-09-23 15:19:57
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With PBDB-T as the Donor, the PCE of Non-Fullerene Organic Solar Cells Based on Small Molecule INTIC Increased by 52.4%
摘要： At present, most high-performance non-fullerene materials are centered on fused rings. With the increase in the number of fused rings, production costs and production difficulties increase. Compared with other non-fullerenes, small molecule INTIC has the advantages of easy synthesis and strong and wide infrared absorption. According to our previous report, the maximum power conversion efficiency (PCE) of an organic solar cell using PTB7-Th:INTIC as the active layer was 7.27%. In this work, other polymers, PTB7, PBDB-T and PBDB-T-2F, as the donor materials, with INTIC as the acceptor, are selected to fabricate cells with the same structure to optimize their photovoltaic performance. The experimental results show that the optimal PCE of PBDB-T:INTIC based organic solar cells is 11.08%, which, thanks to the open voltage (VOC) increases from 0.80 V to 0.84 V, the short circuit current (JSC) increases from 15.32 mA/cm2 to 19.42 mA/cm2 and the fill factor (FF) increases from 60.08% to 67.89%, then a 52.4% improvement in PCE is the result, compared with the devices based on PTB7-Th:INTIC. This is because the PBDB-T:INTIC system has better carrier dissociation and extraction, carrier transportation and higher carrier mobility.
关键词： polymer solar cells (PSCs),synthesize easily,carrier transportation and extraction,carrier mobility,strong and wide infrared absorption,non-fullerene small molecule acceptor
更新于2025-09-23 15:19:57
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Performance improvement of polymer solar cells with binary additives induced morphology optimization and interface modification simultaneously
摘要： Active layer morphology optimization and electrode buffer layer interface modification are commonly used strategies in improving the performance of polymer solar cells (PSCs). In this study, we prepared PTB7: PC71BM bulk heterojunction PSCs with 1,8-diiodooctane (DIO) and polyethylene glycol (PEG) additives, and studied the influence of binary additives on exciton dissociation, charge transport and charge extraction. DIO facilitates donor/acceptor phase separation for efficient exciton dissociation and charge transport. The migration of PEG from active layer to the PEDOT:PSS layer improves the crystallinity of PTB7, optimizes charge transport pathway, and enhances the conductivity of PEDOT:PSS layer. With the combined advantages of binary additives in active layer morphology optimization and anode buffer layer modification, the device exhibits a high short-circuit current density of 20.03 mA/cm2 and an improved power conversion efficiency. Binary additive provides a promising method to optimize active layer morphology and improve interfacial buffer layer of PSCs simultaneously.
关键词： Charge extraction,Charge transport,Binary additive,Polymer solar cells,Morphology,Interface modification
更新于2025-09-23 15:19:57
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Mechanically Robust All-Polymer Solar Cells from Narrow Band Gap Acceptors with Hetero-Bridging Atoms
摘要： A series of polymer acceptors PF2-DTC, PF2-DTSi, and PF2-DTGe with identical molecular backbone but different central bridging atoms in tricyclic-fused donor units were developed. In all-PSCs, the PF2-DTSi-based blend film exhibited excellent mechanical robustness with an impressively high PCE of up to 10.77%. Moreover, the flexible solar cell based on this blend retained >90% of its initial PCE after bending and relaxing 1,200 times at a bending radius of ~4 mm.
关键词： Mechanical robustness,All-polymer solar cells,Narrow band gap acceptors,Power conversion efficiency,Hetero-bridging atoms
更新于2025-09-23 15:19:57
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Theoretical Study of a Class of Organic Da????a??A Dyes for Polymer Solar Cells: Influence of Various ??a??Spacers
摘要： A class of D‐π‐A compounds that can be used as dyes for applications in polymer solar cells has theoretically been designed and studied, on the basis of the dyes recently shown by experiment to have the highest power conversion efficiency (PCE), namely the poly[4,8‐bis(5‐(2‐(PBDTS‐TZNT) butylhexylthio)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b’]dithiophene‐2,6‐diyl‐alt‐TZNT] and poly[4,8‐bis(4‐fluoro‐5‐(2‐butylhexylthio)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b’]dithiophene‐2,6‐ diyl‐alt‐TZNT] (PBDTSF‐TZNT) substances. Electronic structure theory computations were carried out with density functional theory and time‐dependent density functional theory methods in conjunction with the 6?311G (d, p) basis set. The PBDTS donor and the TZNT (naphtho[1,2‐c:5,6‐c]bis(2‐octyl‐[1,2,3]triazole) acceptor components were established from the original substances upon replacement of long alkyl groups within the thiophene and azole rings with methyl groups. In particular, the effects of several π‐spacers were investigated. The calculated results confirmed that dithieno[3,2‐b:2′,3′‐d] silole (DTS) acts as an excellent π‐linker, even better than the thiophene bridge in the original substances in terms of well‐known criteria. Indeed, a PBDTS‐DTS‐TZNT combination forms a D‐π‐A substance that has a flatter structure, more rigidity in going from the neutral to the cationic form, and a better conjugation than the original compounds. The highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) energy gap of such a D‐π‐A substance becomes smaller and its absorption spectrum is more intense and red‐shifted, which enhances the intramolecular charge transfer and makes it a promising candidate to attain higher PCEs.
关键词： DFT calculations,PCEs,DTS,PBDTS‐TZNT and PBDTSF‐TZNT,D‐π‐A dyes,polymer solar cells
更新于2025-09-23 15:19:57
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Toward efficient polymer solar cells with thick bulk heterojunction by introducing iridium complex as an aggregation reshaping auxiliary
摘要： The morphology control of thick bulk heterojunction (BHJ) polymer solar cells (PSCs) is an important factor to determine their power conversion efficiency (PCE). Particularly, during the building of phase separation, aggregation morphology plays a prominent role in the control of both horizonal and vertical gradient distribution of donor/acceptor (D/A) in thick BHJ. In this work, we introduced a novel iridium complex of (tfmppy)2Ir(tpip) into the active layer of PffBT4T-2OD: PC71BM as an “aggregation reshaping auxiliary” to form a long and narrow aggregation shape in both horizontal and vertical directions. Through characterizing the morphology of active layer in details, it was found that the combination of 5% (tfmppy)2Ir(tpip) assists PffBT4T-2OD aggregation shape with a 1: 2.5 aspect ratio while maintaining high crystallinity. In addition, the results showed that the (tfmppy)2Ir(tpip) facilitates efficient exciton dissociation and charge transport because of increased contacting area of D/A interface. As a result, the short circuit current (JSC) and fill factor (FF) performances were both improved contemporaneously, leading to a 20.3% enhancement in PCE.
关键词： Charge transport,Polymer solar cells,Thick bulk heterojunction,Aggregation reshaping auxiliary,Iridium complex
更新于2025-09-23 15:19:57