Spray‐Deposited, Virus‐Templated SnO2 Mesoporous Electron Transport Layer for High‐Efficiency, Sequential‐Deposited Perovskite Solar Cells

In recent years, researchers have developed spray deposition technology to fabricate tin oxide electron transport layer (ETL) with the aim of manufacturing high‐efficiency, large‐area perovskite solar cell (PSC). However, the power conversion efficiency (PCE) of PSC based on sprayed SnO 2 ETL remains inferior to that of the spin‐coated SnO 2 ETL. Herein, the combined use of spray deposition and genetically engineered M13 bacteriophages for the deposition of M13‐SnO 2 biohybrid ETL over large‐area (62.5 cm 2 ) substrates is demonstrated. The spray‐deposited M13‐SnO 2 ETLs exhibit mesoporous morphologies with >85% transmittance in UV–vis region. Through the use of M13‐SnO 2 ETL, the sequential‐deposited PSCs achieve a maximum PCE of ≈22.1%. The improved performance of the PSC is attributable to the mesoporous morphology of M13‐SnO 2 ETL that facilitates the growth of larger perovskite grains. The PSCs based on M13‐SnO 2 ETLs also display highly consistent photovoltaic performance which manifests the excellent scalability of the spraying process. Furthermore, M13‐SnO 2 ‐based PSCs exhibit higher ambient stability compared to the SnO 2 ‐based PSCs, showing that the use of M13 bacteriophage is incredibly beneficial to both the efficiency and stability of PSCs.