 Planar structure-based organometallic perovskite solar cells, OPSCs, are promising alternative to conventional silicon photovoltaics due to their high-power conversion efficiency, PSE. This paper proposes a new IN2S3-based planar heterojunction OPSC architecture and uses SCAPs, 1D simulations to optimize the device's parameters. The simulations show that increasing the perovskite layer thickness leads to higher PSE, reaching a maximum at around 500 nm. Additionally, the simulations reveal that the series resistance and shunt resistance play a major role in determining the OPSC's performance. Under optimal conditions, the OPSC achieves a PSE of over 20%. Furthermore, the OPSC performs best at temperatures between 20 and 30 degrees Celsius, with its efficiency dropping sharply above this range. This article was authored by Devad Dastan, Mustafa K.A. Mohamed, Ali K.A. Moussai, and others.