Transition Metal-Derived 2D Layered Perovskites: A Promising Alternative to Pb in Photovoltaic Systems

The high sensitivity of 3D perovskites toward air and moisture hampers their commercialization due to material decomposition. Introducing their 2D counterparts may provide a remedy to these stability issues, as hydrophobic bulky organic cations can resist direct contact of [${\mathrm{MX}}_6]{}^{4-}$ sheets with moisture in the air. In addition to air and water stability, 2D perovskites offer tunable optoelectronic properties through structural modulation, similar to their 3D counterparts. In this study, six different transition metal (TM)-based 2D hybrid halide perovskites are designed: ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PdCl}}_4$, ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PdBr}}_4$, ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PdI}}_4$, ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PtCl}}_4$, ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PtBr}}_4$, and ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PtI}}_4$ as alternatives for Pb-based perovskites. Analysis of structural and thermodynamic parameters demonstrate that these designed perovskite materials can form structurally and thermodynamically stable compounds. Additionally, optical properties analysis reveals that the intended compounds exhibit absorption maxima in the visible range of the electromagnetic spectrum. Among the designed compounds, ${\left(\mathrm{TTMA}\right)}_2{\mathrm{PtI}}_4$ shows a promising power conversion efficiency (PCE) of 19.63%. Thus, these designed 2D perovskite materials hold potential as substitutes for conventional 3D materials in photovoltaic applications.