Heterogeneous Amine with Polycyclic‐Aromatics‐Modified Hole Transport Material for Efficient and Operationally Durable Perovskite Solar Cells

Abstract Achieving efficient perovskite solar cells (PSCs) with high operational durability is a challenging task. Here, by exploiting the heterogeneous amine strategy at the molecular level, a novel spirobifluorene derivative bearing methoxynaphthalene and 9,9‐dimethylfluorene heterogeneous amine peripheral groups ( N 2 , N 2′ , N 7 , N 7′ ‐tetrakis(9,9‐dimethyl‐9 H ‐fluoren‐2‐yl)‐ N 2 , N 2′ , N 7 , N 7′ ‐tetrakis(6‐methoxynaphthalen‐2‐yl)‐9,9′‐spirobi[fluorene]‐2,2′,7,7′‐tetraamine, denoted as Spiro‐NADF) as a hole transport material (HTM) is developed to address the efficiency and durability issues of PSCs. Compared with 2,2′,7,7′‐tetrakis( N , N ‐di‐ p ‐methoxyphenyl)‐amine‐9,9′‐spirobifluorene, Spiro‐NADF exhibits not only favorable energy level alignment but also a higher glass transition temperature and strong adhesion to perovskite. Moreover, Spiro‐NADF‐based transport layer shows excellent morphological stability in devices against damp heat stress. These advantages reduce voltage loss and suppress perovskite decomposition and ion migration. Consequently, PSCs based on Spiro‐NADF exhibit a champion efficiency of 24.66% with an open‐circuit voltage of 1.19 V. The corresponding cells show greatly enhanced operational durability against harsh environments, retaining over 92% of the initial efficiencies for 500 h aging under a damp heat test (85 °C and 70–90% relative humidity) and illumination under the maximum power point tracking, respectively. This work demonstrates that molecular engineering of HTMs using heterogeneous amines with polycyclic aromatics leaves considerable room for developing efficient and stable PSCs.