A strong candidate for photovoltaic technology, perovskite-based solar cells with a planar structure offers a very high power conversion efficiency (PCE). In the meantime, the strive for lead-free perovskites solar cells (PSCs) is also enhanced owing to the extremely hazardous and carcinogenic nature of lead. Due to their advantageous physical, chemical, optoelectronic, and stability properties, hybrid antimony-based materials have been proposed as an alternative and potential replacement for hazardous lead-based perovskite with the aim of obtaining harmful lead-free PSCs. Recombination in the perovskite layers reduces the performance of hetero-junction-based devices. The homojunction is suited for further PCE improvement because of the electric field that is already there; this will increase the transmission of photo-generated charge carriers while reducing recombination losses. The present work is a comprehensive analysis of planar homojunction perovskite photovoltaic devices based on MA3Sb2I9. Our study reports that the reported PSCs have PCE of 19.84% for the AM1.5 solar spectrum. Additionally, pn-homojunction has been added, which increases the efficiency of the reported device to 21.16%. Thus, this study indicates that the lead-free PSCs are extremely promising and they can be designed for a wide range of photovoltaic applications.