Achieving 19% Power Conversion Efficiency in Planar-Mixed Heterojunction Organic Solar Cells Using a Pseudosymmetric Electron Acceptor

作者：Gao, Wei; Qi, Feng; Peng, Zhengxing; Lin, Francis R.; Jiang, Kui; Zhong, Cheng^*; Kaminsky, Werner; Guan, Zhiqiang; Lee, Chun-Sing; Marks, Tobin J.; Ade, Harald^*; Jen, Alex K-Y^*

来源：Advanced Materials, 2022, 34(32): 2202089.

DOI：10.1002/adma.202202089

• electron acceptors
• free charge generation
• organic solar cells
• planar-mixed heterojunctions
• pseudosymmetry

A record power conversion efficiency (PCE) of over 19% is realized in planar-mixed heterojunction (PMHJ) organic solar cells (OSCs) by adopting the asymmetric selenium substitution strategy in making a pseudosymmetric electron acceptor, BS3TSe-4F. The combined molecular asymmetry with more polarizable selenium substitution increases the dielectric constant of the D18/BS3TSe-4F blend, helping lower the exciton binding energy. On the other hand, dimer packing in BS3TSe-4F is facilitated to enable free charge generation, helping more efficient exciton dissociation and lowering the radiative recombination loss (Delta E-2) of OSCs. As a result, PMHJ OSCs based on D18/BS3TSe-4F achieve a PCE of 18.48%. By incorporating another mid-bandgap acceptor Y6-O into D18/BS3TSe-4F to form a ternary PMHJ, a higher open-circuit voltage (V-OC) can be achieved to realize an impressive PCE of 19.03%. The findings of using pseudosymmetric electron acceptors in enhancing device efficiency provides an effective way to develop highly efficient acceptor materials for OSCs.

• 单位
  西北大学; 武汉大学