Low temperature synthesis of Cs2AgBiBr6 lead-free perovskite for flexible photodetector

All-inorganic Cs₂AgBiBr₆ film is one of most promising materials in the perovskite family for long-term daily life photodetection applications, due to its fairly nice stability and lead-free nontoxic property. However, high annealing temperature (> 250  °C) process is widely used and low temperature synthesis of high-quality Cs₂AgBiBr₆ is still a big challenge, which limits the development toward flexible device. Herein, we developed a Mn doping solution route for Cs₂AgBiBr₆ perovskite which is the first reported element doping process that can effectively improve the film quality under low annealing temperature. The corresponding flexible photodetectors exhibit favorable self-power characteristics and satisfying photoelectric performance with high detectivity of > 10¹⁰ Jones, μs level response speed and large LDR over 110 dB. Such good performance can be maintained even at 120 °C fabrication process. The material properties, device performances and doping mechanism are systematically discussed in the paper. To our knowledge, this is one of the lowest temperature fabrication processes for high performance flexible Cs₂AgBiBr₆ devices. Our results suggest a feasible method and indicate the promising application of Cs₂AgBiBr₆ films for flexible photovoltaic devices.