Narrow Results

Halide perovskite materials such as FAPbI3 are of great interest for photovoltaic applications and could replace silicon cells if problems of chemical instability, strain and crystal defects are solved. In this paper we present a preliminary modeling study of lattice relaxation in epitaxial FAPbI₃ on MAPbCl_xBr_3-x (001).

We have implemented the Coupled-Cluster Equation of Motion (CC-EOM) with single and double excitations coupled with semiempirical parameterizations, Pariser–Parr–Pople model and INDO Hamiltonians, to investigate the optical and nonlinear optical properties, electronic structures and the excited states properties for the conjugated polymers. The semiempirical parameters allow us to study the conjugated systems with extensive sizes. Firstly, by comparing with the quasi-exact Density Matrix Renormalization Group theory for the 1D conjugated chain, we find that the CC-EOM approach can give satisfactory results for both the ground state and the excited states energies. We demonstrate that our approach can be adopted to evaluate linear and nonlinear response. We find that both the real and imaginary parts of the third-order polarizability can be solved either for static and dynamic responses. Then we apply the CC-EOM approach to study the optical signatures for the polarons in conjugated polymers. We have established a solid relationship between the rigidity of a polymer and its optical signature of the polarons.

Halide perovskite materials such as FAPbI₃ are of great interest for photovoltaic applications and could replace silicon cells if problems of chemical instability, strain and crystal defects are solved. In this paper we present a preliminary modeling study of lattice relaxation in epitaxial FAPbI₃ on MAPbCl_xBr_3-x (001).