Interfacial halogen bonding with charge-transport layers for operational stability of hybrid perovskite solar cells

Abstract

Hybrid metal halide perovskites have emerged as some of the leading semiconductors in photovoltaics. Despite their remarkable power conversion efficiencies, these materials remain unstable under device operating conditions. One of the main instabilities relates to the interface with the contact layers in photovoltaic devices, such as metal oxides. We rely on halogen bonding (XB) using 1,4-diiodotetrafluorobenzene (TFDIB) to modulate the interface of the TiO₂ electron-transport layer, demonstrating the improvement of perovskite solar cell operational stability. Furthermore, we complement this strategy with the use of iodo-functionalized Zn–phthalocyanine modulator of the hole-transporting material, which passivate the interface while enhancing the power conversion efficiency, showcasing the potential of XB in hybrid photovoltaics.