Lattice relaxation effect in Rb x MA (1− x ) PbBr 3 single crystal to enhance optoelectronic performance of perovskite photodetectors

Single crystal (SC) MAPbBr 3 perovskite is regarded as a promising material to fabricate high-performance photodetectors (PDs) due to its impressive optoelectronic properties and good chemical stability. Rb + doping has been proved to be an effective method to significantly improve the optoelectronic properties of MAPbBr 3 SC. However, the intrinsic effect of Rb + on the crystal structure is still unclear. Herein, Rb-doping enhances optoelectronic performance of Rb x MA (1 −x ) PbBr3 single crystals by lattice relaxation effect was proved. The density functional theory (DFT) calculations demonstrate that Rb-doping leads to lattice relaxation effect which is benefit to reduce trap density of Rb x MA (1 −x ) PbBr 3 SCs. And then a series Rb x MA (1 −x ) PbBr 3 SCs were grown. X-ray rocking curves (XRC) of Rb x MA (1 −x ) PbBr 3 SCs prove that appropriate Rb-doping concentration could reduce defect density effectively. X-ray photoelectron spectroscopy (XPS) measurements indicate that Rb-doping enhances the atoms interaction in Rb x MA (1 −x ) PbBr 3 lattice. Single-crystal PDs were fabricated to compare the optoelectronic properties of MAPbBr 3 SCs with different Rb-doping concentration, and the 2% Rb-doped Rb x MA (1 −x ) PbBr 3 PD shows the optimum performance.