Ligand-free Cs2PdBr6 perovskite microcrystals with narrow bandgap and high photoelectrochemical performance in aqueous solution

The exploration of efficient lead-free perovskite photoelectric active materials to develop high-performance photoelectrochemical (PEC) systems in aqueous solution is crucial to expand their PEC applications. Herein, we successfully constructed a high-performance PEC platform using ligand-free perovskite Cs₂PdBr₆ microcrystals (MCs) as the photoactive substance. The Cs₂PdBr₆ MCs showed narrow bandgap, wide absorption range, high electronic mobility and good stability in aqueous solutions. Particularly, the Cs₂PdBr₆ MCs exhibited an excellent photoresponse, the photocurrent density could reach as high as 98 μA/cm² under 10.18 mW/cm² light irradiation in the absence of other electron acceptors. In addition of the extremely wide range of response wavelength, wide pH range and accelerated interfacial carrier transfer, the Cs₂PdBr₆ MCs demonstrated the significant potential of photocathode active material for applications in PEC sensors and optoelectronic devices. Therefore, this work indicates that Cs₂PdBr₆ MCs design is a highly efficient way to solve the intrinsic issues of perovskite material, predicting a promising strategy for high performance PEC application in aqueous ambience.