(164i) First-Principles Mechanism Study on Distinct Optoelectronic Properties of Cl-Doped 2D Hybrid Tin Iodide Perovskite

Two-dimensional (2D) Ruddlesden-Popper (RP) hybrid organic inorganic perovskite (HOIP) has emerged as a great alternative to conventional three-dimensional (3D) counterpart, owing to its superior structural integrity in humid conditions. Despite extensive studies on halide doping in 3D perovskite for better optoelectronic properties, understanding of optoelectronic properties through doping engineering to the 2D-RP perovskite is still immature. Using density functional theory (DFT) calculations, we evaluate the optical and electronic properties of Cl-doped lead-free 2D-RP hybrid perovskite, (CH₃(CH₂)₃NH₃)₂(CH₃NH₃)Sn₂I_7-xCl_x. We calculate key functional descriptors such as the electronic band structures, high-frequency dielectric constant, exciton binding energy and absorption spectrum. The properties are additionally analyzed from the aspect of atomic level chemical bonds between Sn and halide, X (I and Cl). We demonstrate that the incorporation of Cl into 2D-RP HOIPs should enhance excitonic property and form strong local ferroelectric domains, which reduces charge recombination rate. Yet, degradation of absorption intensity in the visible light regime observed in Cl-doped 3D system is not noticeable in 2D counterpart. Our ab-initio results propose a smart design principle and elucidate the mechanism for the optoelectronic functionality of Cl-doped low dimensional hybrid perovskite optimized for various electronic devices.