Interlayer engineering in metal halide perovskite photovoltaics

Abstract

Interlayers (ILs) play a pivotal role in perovskite solar cells, enabling efficient charge extraction, suppressing recombination and enhancing device stability. Positioned between the light-absorbing perovskite layer and the electrodes, ILs facilitate selective carrier transport while mitigating interfacial losses. Unlike GaAs cells and heterojunction with intrinsic thin layer silicon cells, which benefit from coherent, chemically compatible interfaces, perovskite solar cells exhibit structural and energetic mismatches at the interfaces between the perovskite and charge transport layers (CTLs). To address these challenges, functional interfacial ILs are introduced at both the CTL/perovskite and CTL/electrode interfaces. This Review examines the evolution of these ILs, from simple passivation layers to multifunctional components that regulate electric fields and carrier dynamics. We highlight recent advances in materials and architectures, classify ILs by their device position and discuss design strategies inspired by mature photovoltaic technologies. We argue that interfacial IL engineering is crucial to radiative efficiency and stable, high-performance perovskite solar cells.