Simultaneous Interfacial Modification and Crystallization Control by Biguanide Hydrochloride for Stable Perovskite Solar Cell with PCE of 24.4%

Abstract

Interfacial modification that serves multiple roles is vital for the fabrication of efficient and stable perovskite solar cells. Here, a multi-functional interfacial material, biguanide hydrochloride (BGCl), is introduced between SnO2 and perovskite to enhance electron extraction as well as crystal growth of perovskite. The BGCl can chemically link to the SnO2 through Lewis coordination/electrostatic coupling and help to anchor the PbI2. Better energetic alignment, reduced interfacial defects and homogeneous perovskite crystallites are achieved, yielding an impressive certified power conversion efficiency (PCE) of 24.4%, with an open circuit voltage of 1.19 V and a drastically improved fill factor of 82.4%. More importantly, the unencapsulated device maintains 95% of its initial PCE after aging for over 500 h at 20 ℃ and 30% relative humidity in ambient conditions. These results suggest that the incorporation of BGCl is a promising strategy to modify the interface and control the crystallization of the perovskite, towards the attainment of highly efficient and stable perovskite solar cells as well as other perovskite-based electronics.