Tuning the morphology and optoelectronic properties of AgBiI4 film through isopropanol treatment

Lead-free halide perovskites have great potential as stable and nontoxic optoelectronic materials. As a promising photovoltaic candidate, AgBiI4 has attracted attention due to its eco-friendly properties and strong stability, but the energy conversion efficiency (PCE) is still low and more effort towards improving the film quality is needed for photovoltaic applications. Here, we synthesized AgBiI4 films by antisolvent treatments with chlorobenzene (CB), toluene (TL), and isopropanol (IPA), respectively, and the corresponding solar cells of ITO/SnO2/AgBiI4/PTAA/Au were fabricated. Our data indicate that the IPA-treated AgBiI4 film has better microstructural quality and higher photovoltaic performance than the other-treated films. Furthermore, the PCE of the cells is enhanced from 0.82% to 1.61% upon IPA-treatment. This study suggests that besides a suitable relative polarity, an antisolvent with a lower boiling point and a higher miscibility with the host solvent is preferred in improving the AgBiI4 film quality and enhancing the photovoltaic performance of AgBiI4-based solar cells.