Comprehensive Study on Optical, Electrical, and Stability Properties of BA2PbBr4-xClx (x = 0, 2, and 4) Ruddlesden Popper Perovskites for High-Performance PeLEDs

Two-dimensional (2D) perovskites in the Ruddlesden Popper (RP) structure are commonly employed in optoelectronic applications. This research introduces BA2PbBr4-xClx (x=0, 2, and 4) as a mixed-halide 2D perovskite material for use in the active layer of perovskite light-emitting diodes (PeLEDs). By utilizing density functional theory (DFT), the electrical, optical, and stability properties of BA2PbBr4-xClx, which have not been previously reported, are investigated. The results show that with an increasing value of x, the bandgap energy shifts towards higher energies (blue shift), while the refractive index decreases. In addition, we demonstrate the band-edge orbitals by analyzing the partial density of states (PDOS) and observing the effect of halide change on them. In the case of x=0 (BA2PbBr4), the thermodynamic stability is lower compared to the other two states: BA2PbBr4Cl2 (x=2) and BA2PbCl4 (x=4). The thermal stability of these materials is studied using the ab initio molecular dynamic (AIMD) method. Furthermore, the stability of these materials in relation to water is also investigated, aligning with the results of thermodynamic stability. The research also explores the influence of strain on bandgap and refractive index. The results show that all three materials are thermodynamically stable, with direct and large band gaps suitable for blue PeLED applications.