Effective Light Trapping Structures in Perovskite Solar Cells with Tunable‐Refractive‐Index Microlens Arrays

ABSTRACT Constructing light‐trapping structures on the surface of perovskite solar cells (PSCs) is an effective strategy to enhance power conversion efficiency (PCE). In this study, we report a scalable microlens array (MLA) as an efficient light‐trapping structure. Four high‐refractive‐index photoresists ( n = 1.60–1.71) are prepared by doping Zirconium oxide nanoparticles (ZrO 2 NPs) into low‐refractive‐index photoresist; subsequently, we fabricate tunable refractive index MLAs with superior morphology and excellent optical performance via optimization of the photolithography process. The optical pathways in PSCs with different light‐trapping structures are investigated by means of Monte Carlo ray‐tracing simulations, and the relationship between the refractive index of MLAs and light manipulation as well as absorption enhancement is systematically analyzed based on these simulation results. In n ‐ i ‐ p perovskite solar cells, the optimized MLAs with a fill density of 22.67% and a refractive index of 1.61 boosts PCE from 25.04% to 26.16%, corresponding to a 4.47% enhancement, primarily attributed to the notable increase in short‐circuit current density ( J SC ). Furthermore, this light‐trapping structure achieves an efficiency enhancement of 8.22% in the indoor perovskite solar module. In this study, novel materials and strategies are proposed for developing highly efficient, large‐area compatible light‐trapping structures, providing a universal approach to enhance PCE of PSCs.