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Highly thermally stable all-polymer solar cells enabled by photo-crosslinkable bromine-functionalized polymer donors
摘要： Here, high performance polymers bearing photo-crosslinkable function are developed for all-PSCs to achieve both high efficiency and stability. Then, a series of novel -(D-A)a-(D-D1)b-type photo-crosslinkable bromine (Br)-functionalized polymer donors PBDT(T)FTAZ-BX were synthesized, in which typical benzodithiophene (BDT) derivative was as first component (D), thiophene-difluoro-benzotriazole (FTAZ) derivative was as second component (A), new simple BDT-based functionality appended Br-unit synthesized in this study was as third component (D1). The effects of Br-functionalized component on the photoelectric properties of the polymers were investigated. Moreover, UV-mediated photo-crosslinking effects on performance and thermal stability were thoroughly explored. All-PSCs based on these photo-crosslinkable polymers and N2200, but without photo-crosslinking, displayed a highest PCE of 7.21%, which was achieved by an optimized PBDT(T)FTAZ-B5-based device. As results, photo-crosslinked PBDT(T)FTAZ-B5 + UV5min-based devices afford extraordinarily excellent thermal stability, in which high retention rate of 91.8% of the maximum PCEavg and the intrinsic performance (PCEmax: 6.12%) are maintained even after 72 h 150 °C annealing. For comparison, reference PBDT(T)FTAZ-based devices only display PCEmax value of 5.13% and retain 84.2% of their maximum PCEavg under same aging. This contrasting result indicates that developing photo-crosslinkable Br-functionalized polymers is an effective strategy to further advance in both stability and efficiency of all-PSCs.
关键词： Bromine-functionalized,All-polymer solar cells,Thermal stability,Photo-crosslinkable
更新于2025-09-23 15:19:57
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Narrow bandgap difluorobenzochalcogenadiazole-based polymers for high-performance organic thin-film transistors and polymer solar cells
摘要： A bithiophene donor unit, 3-alkoxy-3’-alkyl-bithiophene (TRTOR), was copolymerized with difluorobenzochalcogenadiazole (ffBZ) containing different heteroatoms on their diazole structure to afford a series of PffBZ copolymers (where Z = X, T, Se) with narrow optical bandgaps in the range of 1.34-1.47 eV. The effects of ffBZ heteroatoms (O, S, and Se) on the optical properties, electrochemical characteristics and film morphologies of polymers as well as device performance were fully investigated. The results revealed that the highest occupied molecular orbitals (HOMOs) of polymers are gradually elevated accompanied by increased material solubility in common organic solvents as the size of heteroatoms increases. The PffBZ copolymers exhibit substantial hole mobility of 0.08-1.6 cm2 V-1 s-1 in organic thin-film transistors (OTFTs). The PffBX, PffBT, and PffBSe-based polymers exhibit maximum power conversion efficiencies (PCEs) of 5.47%, 10.12%, and 3.65%, respectively in polymer solar cells (PSCs). For PffBZ copolymers, the alkyl chain exerts a great influence on the morphology of the polymer:PC71BM blend films and hence affect PCEs in PSCs. It was found that the performing of polymers branching on the 2nd position for alkyl chain and the 3rd position for alkoxy chain were the best among PffBT and PffBSe-based polymers, and it is different from the tetrathiophene-based benchmark polymer branching on the 2nd position of the alkyl chain. X-ray diffraction revealed that all PffBZ-based polymers has obvious a face-on dominated orientation, and that chalcogen atom and branched position on alkoxy chain have a great influence on the morphologies of neat and blend films. The above results indicated that the branching positions and chalcogen atoms should be carefully optimized to maximize performance.
关键词： polymer solar cells,high-performance,difluorobenzochalcogenadiazole,organic thin-film transistors,narrow bandgap
更新于2025-09-23 15:19:57
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Improved Average Figure-of-Merit of High-Efficiency Non-Fullerene Solar Cells via Minor Combinatory Side Chain Approach
摘要： The cost-effectiveness for polymer solar cells is a very important concern for future application. In this work, a new combinatory side chain integrating siloxane terminal and alkoxy group is developed and three polymers PQSi05, PQSi10 and PQSi25 with 5%, 10%, and 25% contents of the siloxane-terminated alkoxy side chain, respectively, are successfully synthesized. As the content of the combinatory side chain increases, the surface energy of the corresponding polymer film would be decreased, showing tunable miscibility in blend films with non-fullerene acceptor IT-4F. Maximum power conversion efficiency (PCE) of 13.56% is achieved in PQSi05:IT-4F based device. The minor (5%) combinatory side chain approach can retain a low synthetic complexity (SC) of 16.58% for PQSi05. Due to the improved device performance, a low figure-of-merit (FOM) of 1.22 can be obtained for the PQSi05:IT-4F blend. Furthermore, the contribution of the IT-4F acceptor is considered for a comprehensive analysis, giving an average SC (ASC) of 39.31% and an average FOM (AFOM) of 2.90. After statistical analysis and calculation, the PQSi05:IT-4F is the best cost-effective active layer to date. Our findings reveal that the introduction of minor combinatory side chain would be a promising strategy to develop high-performing and cost-effective polymer donors.
关键词： siloxane-terminated combinatory side chain,average figure of merit,synthetic complexity,polymer solar cells
更新于2025-09-23 15:19:57
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Bis(thiena??2a??yl)a??2,1, <scp>3a??benzothiadiazolea??diketopyrrolopyrrole</scp> a??based <scp>acceptora??acceptor</scp> conjugated polymers: Design, synthesis, and the synergistic effect of the substituent on their solar cell properties
摘要： Three acceptor–acceptor conjugated copolymers (TBT-DPP, FTBT-DPP, and HFTBT-DPP) with different substituent groups have been synthesized with palladium-catalyzed Stille coupling condensation polymerization assisted with microwave. Polymer solar cells (PSCs) based on these copolymers as the electron donors and PC71BM as the acceptor have been fabricated. The synergistic effect of the substituent between two fluorine atoms and hexyl alkyl chains in bis(thien-2-yl)-2,1,3-benzothiadiazole fragment on their solar cell properties has been investigated. Both the fluorine atoms and the synergistic effect can improve the solubility of the polymers effectively while the excellent thermal stability properties are still retained. Two fluorine atoms (polymer FTBT-DPP) increased the power conversion efficiency of the PSCs twice compared with TBT-DPP (without substituent). The synergistic effect (polymer HFTBT-DPP) decreased that seriously to zero. Density function theory calculations showed that the conjugation level of the polymer backbone is one of key factors. It demonstrates that the synergistic effect of fluorine atoms and alkyl chains in the same fragment does not always work well in improving the PSCs performance.
关键词： polymer solar cells,diketopyrrolopyrrole polymers,acceptor–acceptor conjugated,bis(thien-2-yl)-2,1,3-benzothiadiazole,synergistic effect
更新于2025-09-23 15:19:57
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[IEEE 2020 IEEE Latin America Electron Devices Conference (LAEDC) - San Jose, Costa Rica (2020.2.25-2020.2.28)] 2020 IEEE Latin America Electron Devices Conference (LAEDC) - New Deposition Technique for Inverted Polymer Solar Cells Using ZnO-ETL
摘要： In this research work, efficient inverted polymer solar cells (iPSCs) were fabricated for the first time using simple and low cost spray pyrolysis (SP) technique to deposit ZnO thin film as electron transporting layer (ETL) with the structure of ITO/ZnO/PTB7-Th: PC70BM/V2O5/Ag. The effect of the different number of running cycles with the SP technique on the iPSC performance has been investigated. In addition, a state of the art for iPSCs fabricated by spin coating technique has been used as reference. In the spray pyrolysis technique, ZnO thin films were fabricated by spraying the ZnO precursor solution onto the pre-heated ITO substrate. Two different numbers of running cycles of ZnO were performed, namely, 15R and 20R. By increasing the running cycles of the sprayed ZnO film, the fill factor and the power conversion efficiency were enhanced by 20% and 32 %, respectively. This improvement might be attributed to enhancing the roughness with compacted film formation and the matched band gap between the active layer (PTB7-Th: PC70BM) and the ZnO-ETL. Hence, this promising spray pyrolysis technique might facilitate the commercialization of polymer solar cells based on mass production besides the possibility of improving its efficiency.
关键词： Polymer solar cells,Spray pyrolysis technique,Zinc Oxide deposition,Electron transporting layer
更新于2025-09-23 15:19:57
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Elucidating Roles of Polymer Donor Aggregation in All-Polymer and Non-Fullerene Small-Moleculea??Polymer Solar Cells
摘要： The aggregation behavior of polymers plays a crucial role in determining the optical, electrical, and morphological properties of donor-acceptor blends in both all-polymer solar cells (all-PSCs) and non-fullerene small molecule acceptor-polymer solar cells (NFSMA-PSCs). However, direct comparison of the impacts on two different systems has not been reported, although it is important to design universal polymer donors (PDs). Herein, three PDs with different side chains (P-EH, P-SEH and P-Si) are designed to study the PD aggregation effects on the blend morphology and device performance of both all-PSCs and NFSMA-PSCs. It is observed that the aggregation property of PDs is a critical factor in determining the optimal blend morphologies and ultimately the device performances in both the PSC systems. Furthermore, PD aggregation effects on device performance is significantly more impactful in all-PSCs than in NFSMA-PSCs. The P-Si PD exhibiting the strongest aggregation behavior in a processing solvent produces the most severe phase separation in the blend with a polymer acceptor, resulting in the lowest power conversion efficiency (PCE) of all-PSCs. In contrast, when P-Si is used in an NFSMA-PSC, a well-mixed blend morphology is observed, which results in the highest PCE of over 12%. These different roles dependent on PD aggregation mainly originate from the difference in molecular size of polymer acceptor and small molecule acceptor, which influences the entropic contribution to the formation of blend morphology. Our work provides a comprehensive understanding on the PD aggregation-blend morphology relationship in different all-PSC and NFSMA-PSC systems, which serves as an important guideline for the design of universal PDs for both all-PSCs and NFSMA-PSCs.
关键词： polymer solar cells,all-polymer solar cells,non-fullerene small molecule acceptor-polymer solar cells,polymer donor aggregation,blend morphology,power conversion efficiency
更新于2025-09-19 17:13:59
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A Nonfullerene Acceptor with Alkylthio‐ and Dimethoxy‐Thiophene‐Groups Yielding High‐Performance Ternary Organic Solar Cells
摘要： Herein, an A–D–A-type nonfullerene acceptor (named IDTS-4F) with an alkyl thiophenyl side chain and dimethoxy thiophene bridging unit is reported. The use of an alkyl thiophenyl group is important, as the insertion of sulfur atoms can slightly downshift the highest occupied molecular orbital (HOMO) level of the molecule and allows IDTS-4F to match with state-of-the-art donor polymer PM6 (or PM7). Compared with conventional nonfullerene acceptors, IT-4F, the IDTS-4F molecule, has a smaller optical bandgap and higher lowest unoccupied molecular orbital (LUMO) level, which are beneficial to increase the Voc and Jsc of the devices. Nonfullerene organic solar cell devices are fabricated using IDTS-4F. Although the binary device based on IDTS-4F exhibits a lower fill factor (FF, 70%), the ternary device by incorporating 0.2 of IDTS-4F and 0.8 of IT-4F (with PM6 as the donor polymer) can simultaneously achieve a higher Voc and Jsc, while maintaining the high FF (77%) of IT-4F based system. Morphology characterizations indicate the formation of homogeneous film morphology, the large increase in phase purity and crystallinity, and the reduction in domain size upon addition of crystalline IDTS-4F, while the electron/hole mobilities and recombination losses of the IT-4F system are both maintained.
关键词： polymer solar cells,nonfullerene acceptors,fullerene-free,organic solar cells,ternary solar cells
更新于2025-09-19 17:13:59
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Naphthalene Diimide-Based Terpolymers with Controlled Crystalline Properties for Producing High Electron Mobility and Optimal Blend Morphology in All-Polymer Solar Cells
摘要： We report a series of new n-type random copolymers (P(NDI2OD-Se-Th x) where x = 0, 0.5, 0.7, 0.8, 0.9, 1.0) consisting of naphthalene diimide (NDI), selenophene-2,2’-thiophene (Se-Th), and seleno[3,2-b]thiophene (SeTh) to demonstrate their use in producing efficient all-polymer solar cells (all-PSCs) and organic field-effect transistors (OFETs). To investigate the effect of polymer crystallinity on the performance of all-PSCs and OFETs, we tuned the composition of the Se-Th and SeTh moieties in the P(NDI2OD-Se-Th x) polymers, resulting in enhanced crystalline properties with higher Se-Th ratio. Thus, the OFET electron mobility was increased with higher Se-Th ratio, exhibiting the highest value of 1.38×10?1 cm2 V?1 s?1 with P(NDI2OD-Se-Th 1.0). However, the performance of all-PSCs based on PBDB-T:P(NDI2OD-Se-Th x) showed a non-linear trend relative to the Se-Th ratio and the performance was optimized with P(NDI2OD-Se-Th 0.8) exhibiting the highest power coversion efficiency of 8.30%. This is attributed to the stronger crystallization-driven phase separation in all-polymer blends for higher Se-Th ratio. At the optimal crystallinity of P(NDI2OD-Se-Th 0.8) in all-PSCs, the degree of phase separation, domain purity and the electron mobility were optimized, resulting in enhanced charge generation and transport. Our works describe structure-property-performance relationships to design effective n-type polymers in terms of crystalline and electrical properties suitable for both efficient OFETs and all-PSCs.
关键词： organic field-effect transistors,seleno[3,2-b]thiophene,polymer crystallinity,n-type random copolymers,selenophene-2,2’-thiophene,charge generation,all-polymer solar cells,charge transport,naphthalene diimide
更新于2025-09-19 17:13:59
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Pronounced Dependence of Alla??Polymer Solar Cells Photovoltaic Performance on the Alkyl Substituent Patterns in Large Bandgap Polymer Donors
摘要： For all-polymer solar cells which are composed of polymer donors and polymer acceptors, the effect of alkyl side chains on photovoltaic performance is a matter of some debate, and this effect remains difficult to forecast. In this concise contribution, we demonstrate that three alkyls namely branched alkyl 2-butyloctyl (2BO), long linear alkyl n-dodecyl (C12), and double-short linear alkyl n-hexyls (DC6) incorporated into the side chains of large bandgap polymer donor PBDT-TTz can induce considerable, of significance, and different electronic, optical, and morphological parameters. Systematic studies shed light on the critical role of the double-short linear alkyl n-hexyls (DC6) in (i) producing large ionization potential value, (ii) increasing propensity of the polymer to order along the π-stacking direction, (iii) generating polymer crystallites with more preferential “face-on” orientation, consequently, (iv) improvement of carriers transportation, (v) suppression of charge recombination, (vi) reduction of energy loss in all-polymer devices. In parallel, we unearth that the PBDT-TTz with double-short linear alkyl n-hexyls (DC6) represents the highest efficiency of 8.3%, whereas, the other two PBDT-TTz analogues (2BO, C12) yield efficiencies of less than 3% in optimized all-polymer solar cells. Though branched or long linear alkyl side chains (2BO, C12) have been applied to provide the solution processability of conjugated polymers, motifs bearing multiple short linear alkyl substituents (DC6) are proved critical to the development of high performing polymers.
关键词： polymer donor,bulk-heterojunction,alkyl substituent,side chain,polymer solar cells
更新于2025-09-19 17:13:59
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Enhanced solar cell performance of P3HT:PCBM by SnS nanoparticles
摘要： In this research, un- and zinc (Zn)-doped tin sulfide (SnS) nanoparticles (NPs) were synthesized by ultrasound method and added to the active layer of ITO/PEDOT:PSS/P3HT: PCBM/Al polymer solar cells (PSCs). The structural, optical, and electrical properties due to the influence of NPs on solar cell performance were investigated. The X-ray diffraction (XRD) patterns of the NPs indicates the formation of orthorhombic polycrystalline SnS. Field emission scanning electron microscopy (FESEM) images show spherical particles with size less than 100 nm for un- and Zn-doped SnS samples. Optical analysis of the cells shows a decrease in the band gap due to the presence of un- and Zn-doped SnS NPs. Photovoltaic characterization of the samples shows that by adding NPs to the polymer film, the device performance improves significantly compared to the absence of NPs. The presence of NPs with different concentrations and structural defects affects the electro-optical properties of the samples.
关键词： P3HT:PCBM,Polymer solar cells,Tin sulfide nanoparticles,Physical properties
更新于2025-09-19 17:13:59