Bright future by enhancing the stability of methylammonium lead triiodide perovskites thin films through Rb, Cs and Li as dopants

This paper deals with the doping of methylammonium lead iodide (MAPbI3) with small amounts of rubidium (Rb), lithium (Li) and caesium (Cs) to improve the crystallisation of MAPbI3 films. Doping significantly increases the peak the (110) diffraction peak, which is related to enhanced crystallisation. The peak located at 148 cm−1 dominates all the Raman spectra in the doped MAPbI3, which is characterised by a central vibrational band corresponding to the symmetric vibration of the anion sublattice. The microstructures of these improved films are characterised by large grain sizes and a uniform surface morphology with no pinholes. Consequently, these films are suitable for high-performance optoelectronic devices. The influence of Li, Rb, and Cs doping on the photophysical properties of MAPbI3 perovskite films is investigated by a photoluminescence analysis. Doping with 5% Li cations increases photoluminescence emissions due to the reduction in the density of trap states. These findings provide fundamental insights into the crystallisation process of MAPbI3 and offer new approaches for developing stable and high-performance devices based on MAPbI3.