Atomic Layer Deposited ZnO–SnO2 Electron Transport Bilayer for Wide‐Bandgap Perovskite Solar Cells

Abstract

High‐quality electron transport layer (ETL) is a prerequisite for high‐performance wide‐bandgap mixed‐halide perovskite solar cells (PSCs), which is critical for efficient perovskite/silicon tandem solar cells. Herein, an atomic layer deposited ZnO–SnO2 bilayer ETL for wide‐bandgap PSCs is reported, featuring a high uniformity and conformality over a large area. The ZnO–SnO2 bilayer shows a matched band alignment with wide‐bandgap perovskite for efficient electron extraction and transport, with a lower nonradiative recombination. As a result, a champion power conversion efficiency of 18.1% is achieved on the ZnO–SnO2 bilayer‐based wide‐bandgap PSCs featuring an ultrahigh open‐circuit voltage (Voc) of 1.233 V, which is the highest value for wide‐bandgap PSCs without any surface passivation. In addition, the atomic layer deposition ZnO–SnO2 bilayer exhibits very good surface passivation and conformality on crystalline silicon surfaces, which makes it attractive to be applied for perovskite/silicon tandem solar cells with a higher Voc and textured surfaces.