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- Chen, Qiaonan, 1992, et al.
(författare)
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Effects of Flexible Conjugation-Break Spacers of Non-Conjugated Polymer Acceptors on Photovoltaic and Mechanical Properties of All-Polymer Solar Cells
- 2022
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Ingår i: Nano-Micro Letters. - : Springer Science and Business Media LLC. - 2311-6706 .- 2150-5551. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Highlights: A series of non-conjugated acceptor polymers with flexible conjugation-break spacers (FCBSs) of different lengths were synthesized.The effect of FCBSs length on solubility of the acceptor polymers, and their photovoltaic and mechanical properties in all-polymer solar cells were explored.This work provides useful guidelines for the design of semiconducting polymers by introducing FCBS with proper length, which can giantly improved properties that are not possible to be achieved by the state-of-the-art fully conjugated polymers. Abstract: All-polymer solar cells (all-PSCs) possess attractive merits including superior thermal stability and mechanical flexibility for large-area roll-to-roll processing. Introducing flexible conjugation-break spacers (FCBSs) into backbones of polymer donor (PD) or polymer acceptor (PA) has been demonstrated as an efficient approach to enhance both the photovoltaic (PV) and mechanical properties of the all-PSCs. However, length dependency of FCBS on certain all-PSC related properties has not been systematically explored. In this regard, we report a series of new non-conjugated PAs by incorporating FCBS with various lengths (2, 4, and 8 carbon atoms in thioalkyl segments). Unlike common studies on so-called side-chain engineering, where longer side chains would lead to better solubility of those resulting polymers, in this work, we observe that the solubilities and the resulting photovoltaic/mechanical properties are optimized by a proper FCBS length (i.e., C2) in PA named PYTS-C2. Its all-PSC achieves a high efficiency of 11.37%, and excellent mechanical robustness with a crack onset strain of 12.39%, significantly superior to those of the other PAs. These results firstly demonstrate the effects of FCBS lengths on the PV performance and mechanical properties of the all-PSCs, providing an effective strategy to fine-tune the structures of PAs for highly efficient and mechanically robust PSCs.[Figure not available: see fulltext.]
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| 2. |
- Li, Yuxiang, et al.
(författare)
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Influence of backbone modification of difluoroquinoxaline-based copolymers on the interchain packing, blend morphology and photovoltaic properties of nonfullerene organic solar cells
- 2019
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7534 .- 2050-7526. ; 7:6, s. 1681-1689
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Tidskriftsartikel (refereegranskat)abstract
- In order to understand the influence of molecular ordering and orientation on the performance of nonfullerene (NF) solar cells, we synthesized a series of difluoroquinoxaline-based alternating copolymers: starting from poly(2,2′-bithiophene-alt-(2,3-bis(3,4-bis(octyloxy)phenyl)-6,7-difluoroquinoxaline)) (PDFQx-2T), we modified the polymeric backbone by incorporating fluorine atoms (PDFQx-2T2F) or thiophene (PDFQx-3T) or a benzene ring (PDFQx-2TB) in the bithiophene comonomeric unit. The structure modification significantly affected the photovoltaic performance with power conversion efficiencies (PCEs) of 3.95% for PDFQx-2TB:ITIC, 4.82% for PDFQx-2T:ITIC, 4.93% for PDFQx-2T2F:ITIC and 8.13% for PDFQx-3T:ITIC. The dramatic increase in the PCE of PDFQx-3T:ITIC was attributed to improvements in the short-circuit current density (J SC ) and fill factor (FF). From the resonant soft X-ray scattering and grazing incidence X-ray scattering measurements, the PDFQx-3T polymers had well-developed, face-on oriented crystallites, allowing the formation of face-to-face alignment with the face-on ordered ITIC molecules at the interfaces. Also, the PDFQx-3T:ITIC blend films exhibited well intermixed blend morphology with smaller domain spacings. These combined features contributed to efficient charge generation with the highest exciton dissociation probability among the four different polymer:ITIC systems. In addition, dominant face-on orientation of both PDFQx-3T polymers and ITIC acceptors with a balanced crystalline coherence length ratio (CCL polymer /CCL ITIC ) (0.87, based on the out-of-plane (010) diffraction peaks of PDFQx polymers and ITIC acceptors) led to a more balanced charge mobility than other blends, explaining the highest J SC and FF in the PDFQx-3T:ITIC NF devices.
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| 3. |
- Wolkeba, Zewdneh Genene, 1983, et al.
(författare)
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Polymer Acceptors with Flexible Spacers Afford Efficient and Mechanically Robust All-Polymer Solar Cells
- 2022
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 34:6
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Tidskriftsartikel (refereegranskat)abstract
- High efficiency and mechanical robustness are both crucial for the practical applications of all-polymer solar cells (all-PSCs) in stretchable and wearable electronics. In this regard, a series of new polymer acceptors (PAs) is reported by incorporating a flexible conjugation-break spacer (FCBS) to achieve highly efficient and mechanically robust all-PSCs. Incorporation of FCBS affords the effective modulation of the crystallinity and pre-aggregation of the PAs, and achieves the optimal blend morphology with polymer donor (PD), increasing both the photovoltaic and mechanical properties of all-PSCs. In particular, an all-PSC based on PYTS-0.3 PA incorporated with 30% FCBS and PBDB-T PD demonstrates a high power conversion efficiency (PCE) of 14.68% and excellent mechanical stretchability with a crack onset strain (COS) of 21.64% and toughness of 3.86 MJ m-3, which is significantly superior to those of devices with the PA without the FCBS (PYTS-0.0, PCE = 13.01%, and toughness = 2.70 MJ m-3). To date, this COS is the highest value reported for PSCs with PCEs of over 8% without any insulating additives. These results reveal that the introduction of FCBS into the conjugated backbone is a highly feasible strategy to simultaneously improve the PCE and stretchability of PSCs.
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| 4. |
- Filate, Tadele Tamenu, 1994, et al.
(författare)
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Aqueous Processed All-Polymer Solar Cells with High Open-Circuit Voltage Based on Low-Cost Thiophene-Quinoxaline Polymers
- 2024
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 16:10, s. 12886-12896
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Tidskriftsartikel (refereegranskat)abstract
- Eco-friendly solution processing and the low-cost synthesis of photoactive materials are important requirements for the commercialization of organic solar cells (OSCs). Although varieties of aqueous-soluble acceptors have been developed, the availability of aqueous-processable polymer donors remains quite limited. In particular, the generally shallow highest occupied molecular orbital (HOMO) energy levels of existing polymer donors limit further increases in the power conversion efficiency (PCE). Here, we design and synthesize two water/alcohol-processable polymer donors, poly[(thiophene-2,5-diyl)-alt-(2-((13-(2,5,8,11-tetraoxadodecyl)-2,5,8,11-tetraoxatetradecan-14-yl)oxy)-6,7-difluoroquinoxaline-5,8-diyl)] (P(Qx8O-T)) and poly[(selenophene-2,5-diyl)-alt-(2-((13-(2,5,8,11-tetraoxadodecyl)-2,5,8,11-tetraoxatetradecan-14-yl)oxy)-6,7-difluoroquinoxaline-5,8-diyl)] (P(Qx8O-Se)) with oligo(ethylene glycol) (OEG) side chains, having deep HOMO energy levels (∼−5.4 eV). The synthesis of the polymers is achieved in a few synthetic and purification steps at reduced cost. The theoretical calculations uncover that the dielectric environmental variations are responsible for the observed band gap lowering in OEG-based polymers compared to their alkylated counterparts. Notably, the aqueous-processed all-polymer solar cells (aq-APSCs) based on P(Qx8O-T) and poly[(N,N′-bis(3-(2-(2-(2-methoxyethoxy)-ethoxy)ethoxy)-2-((2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-methyl)propyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-(2,5-thiophene)] (P(NDIDEG-T)) active layer exhibit a PCE of 2.27% and high open-circuit voltage (VOC) approaching 0.8 V, which are among the highest values for aq-APSCs reported to date. This study provides important clues for the design of low-cost, aqueous-processable polymer donors and the fabrication of aqueous-processable OSCs with high VOC
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