Broadband absorption enhancement in hole-transport-layer-free perovskite solar cell by grating structure

Recently, the hole transport layer-free planar perovskite solar cells (HTL-free PSCs) have attracted intense attention. However, the poor absorption of light in the wavelengths longer than 800 nm is an important challenge in all configurations of PSCs. In this study, the HTL-free PSC with a gold rectangular grating at back contact is proposed. In order to improve the performance of the solar cell, effects of grating dimensions and periodicity on the absorption of the active layer are numerically investigated. In the improved condition, an absorption enhancement of 25% in the range of 300-1 400 nm is obtained compared with the flat electrode-based structure. These improvements are attributed to the coupling of light to surface plasmon polariton (SPP) modes. Also, the electrical simulation results of the improved solar cell demonstrated short-circuit current density and power conversion efficiency of 27.72 mA/cm2 and 18%, respectively.