Blue-Light-Excited Lead-Free Double Perovskite Cs2Ag0.6Na0.4In0.8Bi0.2Cl6/xKBr(KI) at Room Temperature and Photovoltaic Applications

Lead-free halide double perovskites continue to draw increasing attention in view of their nontoxicity and stability compared to lead-based perovskites. High-end full-color displays and white light illumination are based on blue-light excitation. However, the excitation of blue light of lead-free halide double perovskites Cs 2 AgInCl 6 at room temperature faces a great challenge, which is crucial to its commercial application. In this study, Cs 2 Ag 0.6 Na 0.4 In 0.8 Bi 0.2 Cl 6 / x KBr(KI), which can be excited under blue light, have been synthesized by solid-phase compression method. Under blue-light excitation, Cs 2 Ag 0.6 Na 0.4 In 0.8 Bi 0.2 Cl 6 /16KBr and Cs 2 Ag 0.6 Na 0.4 In 0.8 Bi 0.2 Cl 6 /16KI emit 605 nm orange light and 665 nm red light, respectively. Based on that, orange and red light-emitting devices are fabricated excited by blue light. The performance of blue-light excitation can not only make the double perovskites widely used in light-emitting devices, but also as a light-emitting down-shift layer in photovoltaic devices to improve the performance of photovoltaic modules. With the Cs 2 Ag 0.6 Na 0.4 In 0.8 Bi 0.2 Cl 6 /16KBr, the power conversion efficiency of the Si solar cell increases 4.80% and 8.14% under the sunlight and white light-emitting devices, respectively. The blue-light excitation of lead-free double perovskites at room temperature offers greater development potential in the field of display devices and optoelectronics.