Herein we demonstrate the dry synthesis of CsBi3I10 both as a free-standing material and in the form of homogeneous thin films, deposited by thermal vacuum deposition. Chemical and optical characterization shows high thermal stability, phase purity, and photoluminescence centered at 700 nm, corresponding to a bandgap of 1.77 eV. These characteristics make CsBi3I10 a promising low-toxicity material for wide bandgap photovoltaics. Nevertheless, the performance of this material as a semiconductor in solar cells remains rather limited, which can be at least partially ascribed to a low charge carrier mobility, as determined from pulsed-radiolysis time-resolved microwave conductivity. Further developments should focus on understanding and overcoming the current limitations in charge mobility, possibly by compositional tuning through doping and/or alloying, as well as optimizing the thin film morphology which may be another limiting factor. This journal is

Metal halide perovskite solar cells (PSCs) are of interest for high altitude and space applications due to their lightweight and versatile form factor. However, their resilience toward the particle spectrum encountered in space is still of concern. For space cells, the effect of these particles is condensed into an equivalent 1 MeV electron fluence. The effect of high doses of 1 MeV e-beam radiation up to an accumulated fluence to 10¹⁶ e⁻ cm⁻² on methylammonium lead iodide perovskite thin films and solar cells is probed. By using substrate and encapsulation materials that are stable under the high energy e-beam radiation, its net effect on the perovskite film and solar cells can be studied. The quartz substrate-based PSCs are stable under the high doses of 1 MeV e-beam irradiation. Time-resolved microwave conductivity analysis on pristine and irradiated films indicates that there is a small reduction in the charge carrier diffusion length upon irradiation. Nevertheless, this diffusion length remains larger than the perovskite film thickness used in the solar cells, even for the highest accumulated fluence of 10¹⁶ e⁻ cm⁻². This demonstrates that PSCs are promising candidates for space applications.