Theoretical Study of Bromide Mixed-RbPbI3 Towards Optoelectronic Applications

Structural stability is a severe issue for the perovskite solar cells despite of their superior photovoltaic properties. Compositional engineering is an effective way to deal with the stability, so we have studied the structural, electronic, and optical properties of bromide mixed orthorhombic RbPb(I1-XBrX)(3) (where x = 0.25, 0.50, and 0.75) using density functional theory. The lowest energy band gaps of 2.288 eV and 2.986 eV for bromide mixing of x = 0.50 are obtained using PBE and TB-mBJ, respectively. In contrast, the mixed halide structures possess a smaller effective mass, facilitating a better carrier transport through it. PBE estimates excitons to be the Mott-Wannier type. However, the TB-mBJ predicts the exciton to be Frenkel type for bromide mixing of x = 0.75 and a Mott-Wannier type for all the other mixing under study. The spectroscopic limited maximum efficiency (SLME) was observed to be at the highest value of 14.0% for the equal admixture of I and Br using PBE. The calculated properties are consistent with the reported data of similar structures. [Graphics]

Automated summary

Structural stability is a major concern for perovskite solar cells, but compositional engineering can effectively address this issue. The structural, electronic, and optical properties of bromide mixed orthorhombic RbPb(I1-XBrX)(3) were studied using density functional theory. The lowest energy band gaps of 2.288 eV and 2.986 eV were obtained for bromide mixing of x = 0.50 using PBE and TB-mBJ, respectively. Mixed halide structures showed smaller effective mass, facilitating better carrier transport. PBE predicted Mott-Wannier type excitons, while TB-mBJ predicted Frenkel type excitons for bromide mixing of x = 0.75 and Mott-Wannier type for other mixings. The highest spectroscopic limited maximum efficiency (SLME) of 14.0% was observed for equal admixture of I and Br using PBE. The calculated properties are consistent with reported data of similar structures.