Porphyrin Dimers as Hole-Transporting Layers for High-Efficiency and Stable Perovskite Solar Cells

In this work, we demonstrate the optimum utilization of porphyrin-based hole-transporting materials (HTMs), namely, WT3 and YR3, for fabricating triple-cation perovskite solar cells. These newly designed HTMs based on dimeric porphyrin structure exhibit a good HOMO level, high hole mobility, and great charge extraction ability for perovskite solar cells. Moreover, through proper molecular engineering, dimeric porphyrins WT3 and YR3 are capable of forming films free of pinholes, with more uniform and dense surfaces leading to enhanced device performance. Perovskite solar cells using a WT3 HTM achieve a power conversion efficiency (PCE) of 19.44%, which is higher than that using YR3 (17.84%) and even spiro-OMeTAD (18.62%) under 1 Sun AM 1.5G illumination. In addition, WT3-based devices show better stability than spiro-based counterparts under moisture, light-soaking, and thermal testing conditions.