Melt-Processed Halide Perovskite Thin Films from a Two-Dimensional Ruddlesden-Popper Phase Precursor

J Phys Chem Lett. 2023 Jun 8;14(22):5194-5202. doi: 10.1021/acs.jpclett.2c03916. Epub 2023 May 31.

Abstract

While halide perovskite thin films have enormous potential for photovoltaics and other optoelectronics, the use of environmentally hazardous solvents during their deposition and processing poses a barrier to their commercialization. In this work, we demonstrated the deposition of melt-processable precursors and subsequent transformation into halide perovskite thin films without using environmentally hazardous solvents. We melted the wide-bandgap layered perovskites [(C6H5CH(CH3)CH2NH3)2PbI4:β-Me-PEA2PbI4] at ∼210 °C and blade coated them into films. The β-Me-PEA2PbI4 films were subsequently transformed to perovskite-phase methylammonium or formamidinium lead iodide films using a cation-exchange process in an alcohol-based solvent. Lastly, we demonstrate the potential and limitations of a completely solvent-free approach that uses solid-state transformation of a β-Me-PEA2PbI4 film. This work represents a substantial step toward eliminating environmentally hazardous solvents and enables inexpensive industrial-scale liquid-phase deposition processes that do not require expensive systems for handling and disposing of environmentally hazardous solvents.