Design of ultrathin hole-transport-layer-free perovskite solar cell with near-infrared absorption enhancement using Ag NPs

Hole transfer layer-free perovskite solar cells (HTL-free PSCs) have been proposed to reduce manufacturing costs and improve stability. However, the weak optical absorption of the perovskite layer in the infrared region and ultrathin PSCs design have received less attention. In this study, ultrathin HTL-free PSC based on silver nanoparticles (NPs) at the perovskite layer/back electrode interface is proposed to increase the light trapping. The thickness of the perovskite layer is only 150 nm. The NPs radius is designed based on Mie theory to lead the highest scattering. By employing a numerical analysis, the effect of the periodicity of NPs on the performance of the PSCs is studied to obtain improved structure. The improved structure showed an absorption enhancement of 48% compared with the device without NPs within 300 nm-1400 nm wavelength. Light scattering and near field enhancement supplied by the Ag NPs are responsible for the broadband absorption increase. Photovoltaic characterizations of the improved proposed solar cell are obtained with coupled optical- electrical numerical analysis. The results showed 25.09 mA/cm(2) and 14.96%, respectively, for short-circuit current density and efficiency that the efficiency improved by 56% compared to PSCs without NPs. It is believed that this investigation can provide approaches for the design and production of simple, efficient, and economical PSCs.