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Optimized Molecular Packing and Nonradiative Energy Loss Based on Terpolymer Methodology Combining Two Asymmetric Segments for High-Performance Polymer Solar Cells
摘要： In this work, a random terpolymer methodology combining two electron-rich units, asymmetric thienobenzodithiophene (TBD) and thieno[2,3-f]benzofuran (TBF) segments, is systematically investigated. The synergetic effect is embodied on the molecular packing and nanophase when copolymerization with 1,3-bis(2-ethylhexyl)benzo[1,2-c:4,5-c']dithiophene-4,8-dione (BDD), producing an impressive power conversion efficiency (PCE) of 14.2% in IT-4F based NF-PSCs, which outperformed the corresponding D-A copolymers. The balanced aggregation and better interpenetrating network of the TBD50:IT-4F blend film can lead to mixing region exciton splitting and suppress carrier recombination, along with high yields of long-lived carriers. Moreover, the broad applicability of terpolymer methodology is successfully validated in most electron-deficient systems. Especially, TBD50/Y6-based device exhibits high PCE of 15.0% with a small energy loss (0.52 eV) enabled by the low non-radiative energy loss (0.22 eV), which are among the best values reported for polymers without using BDT unit to date. These results demonstrate an outstanding terpolymer approach with backbone engineering to raise the hope of achieving even higher PCEs and to enrich organic photovoltaic materials reservoir.
关键词： asymmetrical structure,microstructure,random terpolymer,nonfullerene solar cell,non-radiative energy loss,power conversion efficiency
更新于2025-09-23 15:19:57
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Regulation of Molecular Packing and Blend Morphology by Finely Tuning Molecular Conformation for High-Performance Nonfullerene Polymer Solar Cells
摘要： The asymmetric thienobenzodithiophene (TBD) structure is first systematically compared with the benzo[1,2-b:4,5-b′]dithiophene (BDT) and dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene (DTBDT) units in donor-acceptor (D-A) copolymers and applied as the central core in small molecule acceptors (SMAs). Specific polymers including PBDT-BZ, PTBD-BZ, and PDTBDT-BZ with different macromolecular conformations are synthesized and then matched with four elaborately designed acceptor-donor-acceptor (A-D-A) SMAs with structures comparable to their donor counterparts. The resulting polymer solar cell (PSC) performance trends are dramatically different from each other and highly material-dependent, and the active layer morphology is largely governed by the polymer conformation. Due to its more linear backbone, the PTBD-BZ film has higher crystallinity and more ordered and denser π–π stacking than those of the PBDT-BZ and PDTBDT-BZ films. Thus, PTBD-BZ shows excellent compatibility with and strong independence on the SMAs with varied structures, and PTBD-BZ-based cells deliver high power conversion efficiency (PCE) of 10~12.5%, whereas low PCE is obtained by cells based on PDTBDT-BZ due to its zigzag conformation. Overall, this study reveals control of molecular conformation as a useful approach to modulate the photovoltaic (PV) properties of conjugated polymers.
关键词： morphology,nonfullerene solar cell,power conversion efficiency,asymmetrical backbone,molecular conformation
更新于2025-09-12 10:27:22