Spray‐Coated Lead‐Free Cs<sub>2</sub>AgBiBr<sub>6</sub> Double Perovskite Solar Cells with High Open‐Circuit Voltage
Nathan Daem, Jennifer Dewalque, Felix Lang, Anthony Maho, Gilles Spronck, Catherine Henrist, Pierre Colson, Samuel D. Stranks, Rudi Cloots
Abstract
Lead‐free Cs 2 AgBiBr 6 double perovskite is considered a promising alternative photovoltaic absorber to the widely used lead halide perovskite due to its easy processability, high stability, and reduced toxicity. Herein, for the first time spray processing for the deposition of Cs 2 AgBiBr 6 double perovskite thin films is reported. Microstructural (X‐ray diffraction, scanning electron microscopy) and optoelectronic (absorbance, photoluminescence, photocurrent density versus applied voltage curves, electrochemical impedance spectroscopy) properties of spray‐coated film are compared with the spin‐coated benchmark. Incorporation of the spray‐coated Cs 2 AgBiBr 6 double perovskite thin films in solar cells leads to a 2.3% photoconversion efficiency with high open‐circuit voltage of 1.09 V. This study highlights the suitability of ultrasonic spray deposition for the optimization of Cs 2 AgBiBr 6 solar cells in terms of light absorption properties and charge transfer at the Cs 2 AgBiBr 6 /hole transporting layer interface.