Enhancing the Performance of Perovskite Solar Cells by Extending the Terminal Conjugation of Spiro‐Type Hole Transport Material

Hole transport materials (HTM) play a vital role in the performance of perovskite solar cells (PSCs). Optimizing the molecular structure of HTMs has been proven to be an important method for improving PSCs’ efficiency and stability. Herein, a novel dibenzofuran‐terminated spiro‐type HTM with extending π‐conjugation is designed and developed, named spiro‐BNF. The structure–property relationship is also studied with spiro‐OMeTAD and spiro‐DBF as the reference. The results show that spiro‐BNF has improved hole mobility and glass transition temperature (reaching 198 °C) than spiro‐OMeTAD and spiro‐BDF. spiro‐BNF also exhibits matched highest occupied molecular orbital level with perovskite and superior morphology on the perovskite layer. Accordingly, the PSCs employing spiro‐BNF display a higher power conversion efficiency of 23.65% and improved stability than the device employing spiro‐OMeTAD or spiro‐BDF. The findings provide a new insight for enhancing the performance of PSCs.