Perovskite CH₃NH₃PbI_3–xBr_x Single Crystals with Charge-Carrier Lifetimes Exceeding 260 μs

The long carrier lifetimes in perovskite single crystals have drawn significant attention recently on account of their irreplaceable contribution to high-performance photovoltaic (PV) devices. Herein, the optical and optoelectronic properties of CH 3 NH 3 PbI 3 and CH 3 NH 3 PbI 3– x Br x (with five different contents of Br doped) single crystals were investigated. Notably, a superior carrier lifetime of up to 262 μs was observed in the CH 3 NH 3 PbI 3– x Br x (I/Br = 10:1 in the precursor) single-crystal PV device under 1 sun illumination, which is two times longer than that in the CH 3 NH 3 PbI 3 single crystal. Further study confirmed that the ultralong carrier lifetime was ascribed to the integrated superiority derived from both the low trap-state density and high charge-injection efficiency of the device interface. On this basis, appropriate incorporation of Br is useful in the design of better PV devices.