Constructing Sensitive and Fast Lead-Free Single-Crystalline Perovskite Photodetectors

We developed a high-performance photodetector based on (CH3NH3)(3)Sb2I9 (MA(3)Sb(2)I(9)) microsingle crystals (MSCs). The MA(3)Sb(2)I(9) single crystals exhibit a low-trap state density of similar to 10(10) cm(-3) and a long carrier diffusion length reaching 3.0 mu m, suggesting its great potential for optoelectronic applications. However, the centimeter single crystal (CSC)-based photodetector exhibits low responsivity (10(-6) A/W under 1 sun illumination) due to low charge-carrier collection efficiency. By constructing the MSC photodetector with efficient charge-carrier collection, the responsivity can be improved by three orders of magnitude (under 1 sun illumination) and reach 40 A/W with monochromatic light (460 nm). Furthermore, the MSC photodetectors exhibit fast response speed of <1 ms, resulting in a high gain of 10(8) and a gain-bandwidth product of 10(5) Hz. These numbers are comparable to the lead-perovskite single-crystal-based photodetectors.