First-principles calculations into electronic, and excitonic effects of CH3NH3PbX3 (X = Br, I) perovskite solar cells.

The orthorhombic phases of CH 3 NH 3 PbX 3 (X = Br, I) have garnered significant research interest for their potential applications in optoelectronics. This work presents our findings regarding the geometric, electronic, and optical properties of CH 3 NH 3 PbX 3 utilizing first-principles calculations based on density functions theory (DFT), and many-body perturbation theory (MBPT). Our investigation reveals that CH 3 NH 3 PbX 3 exhibits direct band gap semiconductors, low effective mass, and high carrier mobility. Furthermore, CH 3 NH 3 PbX 3 processes interesting optical properties, including a low exciton energy binding, and low reflectivity/high absorption efficiency. Additionally, the identified bound exciton states manifest as bright states in both materials. More importantly, the intimate correlation between optical and electronic characteristics is convincingly established through the orbital hybridization concept. These features suggest that CH 3 NH 3 PbX 3 materials hold promise as an active layer for perovskite-based solar cells. [ABSTRACT FROM AUTHOR]