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Bicomponent-random Approach to Synthesis of Donor Polymers for Efficient All-Polymer Solar Cells Processed from A Green Solvent
摘要： All-polymer solar cells (all-PSCs) can offer unique merits of high morphological stability to thermal and mechanical stress. To realize its full potential as flexible or wearable devices, it is highly desirable that the all-PSCs can be fabricated from green solvent with simple post-treatment to avoid thermal annealing on flexible substrate. This proposed a severely challenge on material design to tune their properties with suitable solubility, aggregation, and morphology. To address this challenge, here, a simple bicomponent-random approach on a D-A-type polymer donor was developed by just varying the D-A molar ratio. Under this approach, a series of new random polymers PBDTa-TPDb with different molar ratio of D component of 2D-benzo[1,2-b:4,5-b']dithiophene (BDT) and A component of thieno[3,4-c]pyrrole-4,6-dione (TPD) were designed and synthesized. The energy levels, light absorption, solubility and packing structure of random donors PBDTa-TPDb were found to vary substantially with the various D-A molar ratio. The devices based PBDTa-TPDb/P(NDI2HD-T) were fabricated to explore the synergistic effects of processing solvent and composition of D-A-type random polymers. The results show that nanoscale morphology, balanced miscibility/crystallinity of blend and photovoltaic properties could be rationally optimized by tuning the composition of random donors. As a result, as-cast all-PSC based optimal donor PBDT5-TPD4 achieves a best power conversion efficiency (PCE) of 8.20% processed from green solvent, which performs better than that based reference polymer (PCE: 6.41%). This efficiency is the highest value for all-PSCs from BDT-TPD-based donors. Moreover, the optimized devices exhibited relatively insensitive to the thickness of the active layer and good stability.
关键词： thieno[3,4-c]pyrrole-4,6-dione,all-polymer solar cells,bicomponent-random approach,benzo[1,2-b:4,5-b']dithiophene,green solvent
更新于2025-09-11 14:15:04
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Comparison of ZnO buffer layers prepared by spin coating or RF magnetron sputtering for application in inverted organic solar cells
摘要： We compared the electrical, optical, structural, and morphological properties of radio-frequency (RF) magnetron-sputtered ZnO and solution-processed ZnO nanoparticle (NP) buffer layers on ITO cathodes for use in inverted polymer solar cells (IPSCs). Continuous sputtering resulted in integration of the ZnO buffer layer in the ITO cathodes, which were then used as transparent cathodes for IPSCs. Although the electrical, optical, and morphological properties as well as work function of RF-sputtered ZnO film were similar to those of solution-processed ZnO NP film, the power conversion efficiency (PCE) of IPSCs with an RF-sputtered ZnO buffer layer was much lower than that of IPSCs with a solution-processed ZnO NP buffer layer due to vertical phase segregation of the organic active layer. However, intentional bias sweeping of IPSCs with an RF-sputtered ZnO buffer layer improved performance due to diffusion of PC70BM through the PV-D4610 donor layer and formation of a suitable heterojunction structure. Based on transmission electron microscope examination and dark current-voltage curves, we suggest a possible mechanism to explain the difference in behavior of RF-sputtered ZnO and solution-processed ZnO NP buffer layers in IPSCs.
关键词： ZnO nanoparticles,Vertical phase segregation,Microstructure,Sputtered ZnO,Inverted polymer solar cells,Buffer layer
更新于2025-09-10 09:29:36
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Ladder‐Type Nonacyclic Arene Bis(thieno[3,2‐b]thieno)cyclopentafluorene as A Promising Building Block for Non‐Fullerene Acceptor
摘要： A ladder-type nonacyclic arene (bis(thieno[3,2-b]thieno)cyclopentafluorene (BTTF)) has been designed and synthesized through fusing thienothiophenes with the fluorene core from the synthon of dimethyl 9,9-dioctyl-2,7-bis(thieno[3,2-b]thiophen-2-yl)fluorene-3,6-dicarboxylate. With BTTF as the central donor unit, a novel acceptor-donor-acceptor (A-D-A) type non-fullerene small molecule (BTTFIC) was prepared with 1,1-dicyanomethylene-3-indanones (IC) as the peripheral acceptor units. The energy level of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of BTTFIC locate at -5.56 and -3.95 eV, respectively, presenting a low optical band gap of 1.58 eV. Encouragingly, polymer solar cells based on the blends of BTTFIC with both the representative wide and low band gap polymer donors (PBDB-T, 1.82 eV. PTB7-Th, 1.58 eV) offer power conversion efficiencies over 8% (8.78 ± 0.18% for PBDB-T:BTTFIC and 8.18 ± 0.29% for PTB7-Th:BTTFIC). These results highlight the advantage of ladder-type BTTF on the preparation of nonfullerene acceptors with extended conjugated backbones.
关键词： Ladder-type Arene,Non-fullerene Acceptor,Bulk heterojunction,Polymer Solar Cells,Polycyclic Aromatics
更新于2025-09-04 15:30:14