Solution-Processed Cesium Hexabromopalladate(IV), Cs₂PdBr₆, for Optoelectronic Applications

Lead halide perovskites are materials with excellent optoelectronic and photovoltaic properties. However, some hurdles remain prior to commercialization of these materials, such as chemical stability, phase stability, sensitivity to moisture, and potential issues due to the toxicity of lead. Here, we report a new type of lead-free perovskite related compound, Cs₂PdBr₆. This compound is solution processable, exhibits long-lived photoluminescence, and an optical band gap of 1.6 eV. Density functional theory calculations indicate that this compound has dispersive electronic bands, with electron and hole effective masses of 0.53 and 0.85 m_e, respectively. In addition, Cs₂PdBr₆ is resistant to water, in contrast to lead-halide perovskites, indicating excellent prospects for long-term stability. These combined properties demonstrate that Cs₂PdBr₆ is a promising novel compound for optoelectronic applications.