Improving photoluminescence properties and reducing recombination of CsPbBr perovskite through lithium doping.

This study investigates the impact of lithium doping on the structural and photophysical properties of spin-coated CsPbBr perovskite thin films. The deposited films display a pristine structure, preferentially growing along the (220) direction, and exhibit high-quality green photoluminescence at around 530 nm. The doping leads to an improvement in the optical properties of the films, as evidenced by a stronger photoluminescence (PL) intensity compared to undoped CsPbBr, particularly at temperatures below 200 K. The increase in PL intensity suggests a decrease in defects and surface passivation. Additionally, the decrease in the power-law exponent from 1.6 to 1.0 indicates a reduction in non-radiative recombination, likely due to trap states filling with free electrons induced by the doping. Overall, doping with lithium reduces non-radiative recombination, fills trap states, and reduces band tail/activation energy, leading to improved optoelectronic properties of the films. This investigation provides insights into the photophysical properties of the Li-CsPbBr absorber layer and the recombination mechanism, and helps to unravel new methods for the development of high-stability, high-performance perovskite thin-film solar cells and optoelectronic devices.