Tuning the molar mass of P3HT via direct arylation polycondensation yields optimal interaction and high efficiency in nonfullerene organic solar cells

作者：Liu, Yang; Xian, Kaihu; Peng, Zhongxiang; Gao, Mengyuan; Shi, Yibo; Deng, Yunfeng^*; Geng, Yanhou^*; Ye, Long^*

来源：Journal of Materials Chemistry A, 2021, 9(35): 19874-19885.

DOI：10.1039/d1ta02253a

• NON-FULLERENE ACCEPTOR
• MOLECULAR-WEIGHT
• AMORPHOUS INTERACTION
• PERFORMANCE
• MORPHOLOGY
• BULK
• OPTIMIZATION
• TRANSPORT

Due to the simple structure and excellent scalability, regioregular poly(3-hexylthiophene) (P3HT) has become much more popular as a low-cost donor polymer partner with the emerging nonfullerene acceptors in recent years. Presently, the application and the molar mass dependence of direct arylation polycondensation (DArP) prepared P3HT in fullerene-free organic solar cells have not been explored yet. In this work, five batches of P3HT with weight-average molar mass ranging from 8.9 kg mol(-1) to 89.1 kg mol(-1) were successfully prepared via DArP, with the aim to detail the interaction-performance relationships in the state-of-the-art P3HT:nonfullerene photovoltaic blend, namely P3HT:ZY-4Cl. Our thermodynamic analysis revealed that the amorphous-amorphous interaction parameters strongly depend on the P3HT molar mass and can be varied by a factor of 2.75. Owing to the best pi-pi stacking order deduced from grazing incidence X-ray diffraction and the smallest domain size, the blend based on the medium molar mass batch (25.5 kg mol(-1)) delivered the highest current density, fill factor, and power conversion efficiency up to similar to 10% among the five systems. Our study confirmed that DArP is an effective protocol for the synthesis of P3HT for efficient non-fullerene polymer solar cells and the established relationships can be applied to screen the best batch for P3HT-based organic photovoltaics.

• 单位
  天津大学