Enhance efficiency in flat and nano roughness surface perovskite solar cells with the use of index near zero materials filter.

Light confinement technologies are especially effective in improving the power conversion efficiency of thin-film perovskite solar cells. For this purpose in this paper, designing an angular filter for these photovoltaic cells using nano-rough structures and index-near-zero materials is proposed. Since perovskites' energy bandgap can be easily tuned by their chemical composition, an optimal structure with typical compounds was proposed that produced the highest power conversion efficiency limit. Besides improving light confinement in the thin, perovskite active layer, the proposed structure improved the solar cell performance by enhancement of short-circuit current and open-circuit voltage through controlling radiative and non-radiative recombination. With these arrangements, an optimal power conversion efficiency limit of 40.01% has been calculated using the detailed-balance method, which indicates a 15.27% improvement compared to the original structure. The Finite-Difference Time-Domain (FDTD) method was used to demonstrate the expansion of the absorption spectrum and calculate the absorption efficiency for presenting an optimal structure design with nano-roughness for different perovskite compounds. [ABSTRACT FROM AUTHOR]