TD-DFT-guided development of a robust hole-transporting layer for optimized triple-cation perovskite solar cell performance

Perovskite solar cells (PSCs) have earned considerable attention as a promising photovoltaic technology for future power generation. Spiro derivatives are often used as a hole-transporting layer (HTL) in highly efficient PSC devices. However, spiro derivatives have low hole mobility and conductivity in their native form and require complicated preparation. Therefore, using other low-cost chemical compounds that are easy to synthesize becomes essential to improve conductivity and, thus, efficiency. The compound MS-T, also known as 4,4′-(thiophene-2,5-diyl)bis(N,N-bis(4-methoxyphenyl) aniline), was intentionally theoretically designed to have a symmetrical structure. It consists of the core of a heterocyclic compound (thiadiazole), with two triphenylamine molecules attached at positions 2 and 5 to improve the electron density of the compound. The modeled PSC was numerically optimized with many significant parameters, including layer thickness, temperature, doping density, defect density, and other characteristics. This optimization was carried out using the SCAPS-1D program. Furthermore, flaws in the interfaces between the electron-transporting layer (ETL)/perovskite and HTL/perovskite were considered, and their impact on performance was also examined. The optimized PSC has an attainable efficiency of up to 30.66%.