Solution-processed lead-free double perovskite microplatelets with enhanced photoresponse and thermal stability

Due to the better stability and environment-friendly nature, lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics; however, to date, their photoelectric device performance is still not satisfactory. Herein, we report a facile solution-process method to synthesize the recently most popular lead-free halide double perovskite, MA₂AgBiBr₆, and its all-inorganic counterpart, Cs₂AgBiBr₆. The obtained MA₂AgBiBr₆ and Cs₂AgBiBr₆ films exhibit the microplatelet morphology with excellent crystallinity, distinctly contrasting the ones fabricated by the conventional spin-coating method. Once fabricated into simple photodetectors, the Cs₂AgBiBr₆ microplatelet devices yield a respectable responsivity of 245 mA W⁻¹ that is two orders of magnitude larger than that of the spin-coated films. More importantly, the response speed of the Cs₂AgBiBr₆ microplatelets device is as fast as 145 µs, which is higher than most of the values reported in the community of halide double perovskites. When subjected to the thermal stability testing, the Cs₂AgBiBr₆ microplatelet device can maintain its initial performance after heating to 160°C and cooling down to room temperature in the ambient environment. All these results suggest that the facile solution-process method is capable of fabricating high-quality lead-free double perovskites, enabling their advanced device applications. [Figure not available: see fulltext.]