Dopant‐Free Hole‐Transporting Materials for Stable and Efficient Perovskite Solar Cells

Molecularly engineered novel dopant‐free hole‐transporting materials for perovskite solar cells (PSCs) combined with mixed‐perovskite (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 (MA: CH 3 NH 3 + , FA: NH=CHNH 3 + ) that exhibit an excellent power conversion efficiency of 18.9% under AM 1.5 conditions are investigated. The mobilities of FA‐CN, and TPA‐CN are determined to be 1.2 × 10 −4 cm 2 V −1 s −1 and 1.1 × 10 −4 cm 2 V −1 s −1 , respectively. Exceptional stability up to 500 h is measured with the PSC based on FA‐CN. Additionally, it is found that the maximum power output collected after 1300 h remained 65% of its initial value. This opens up new avenue for efficient and stable PSCs exploring new materials as alternatives to Spiro‐OMeTAD.