Homogeneous BN/Perovskite Heterostructure with Nanoscale Heat‐Dissipative Pathways for Stable Perovskite Solar Cells

Abstract Perovskite solar cells have emerged as a low‐cost and high‐performance photovoltaic technology, yet suffer from insufficient lifetime, particularly under high temperature condition. Here, a heat‐dissipative boron nitride (BN)/perovskite heterostructure is demonstrated to cool the device under operational conditions. It is shown that the trimethyl phosphate functionalized BN can be uniformly dispersed around perovskite grain boundaries, resulting in trap density reduction and improve thermal conductivity concurrently. Finite element analysis reveals the BN nanosheets function as local thermal dissipation pathways, which rapidly guides the heat flow into outside environments. The thermal management strategy can decline the device operational temperature from 34.6 °C to 21.7 °C under one sun illumination, and enable solar cells with over 95% of maintained efficiency after 2640 hours of operation under simulated AM 1.5G irradiation at 85 °C.