Deciphering halide ion migration and performance loss in wide-bandgap perovskite solar cells: connection, mechanism, and solutions

Abstract

Wide-bandgap (WBG, ≥1.60 eV) mixed-halide perovskites with tunable bandgap are pivotal for advancing tandem photovoltaics (PVs). However, WBG perovskite solar cells (PSCs) suffer from severe performance loss, often linked to halide ion migration (HIM) straightaway. While strategies to suppress HIM have improved device properties, the underlying relation between HIM and device performance remains ambiguous and contentious. In this minireview, we summarize and evaluate the origins of voltage (VOC) and current (JSC) losses and critically assesses their correlation with HIM-driven worsts, such as phase heterogeneity and carrier funneling. Furthermore, we propose research priorities to resolve this matter in a nutshell: (i) mechanistic investigation about iodide(I)-rich terminal (~1.60 eV) domains, such as spatiotemporal resolved mapping and interfacial carrier dynamics; (ⅱ) regulation strategies of i.e., additive and interface engineering to mitigate adverse effects from HIM. By elucidating mechanistic interplay between HIM and performance decay, this work aims to offer more powerful guidance for efficient and photostable WBG perovskite-related PVs.