Hole Transport Role of Perovskite in Thick Film Perovskite Solar Cells without a Rear Blocking Layer

Perovskite solar cells (PSCs) have achieved remarkable efficiencies, largely due to the use of nanoscale light-absorbing layers. This success has led to significant research into scalable fabrication processes for these thin films. Although microscale deposition techniques offer established benefits for large-area manufacturing, PSCs with thicker perovskite layers (exceeding 1 μm) typically exhibit lower efficiencies. This study aims to elucidate the fundamental factors limiting the efficiency of microscale perovskite light absorbers in solar cell devices, with the goal of leveraging the scalability of microscale deposition for high-performance PSCs. We also focused on the excellent hole-transporting properties of perovskites and evaluated their performance potential in the absence of a rear blocking layer (RBL). Thick perovskite films with thicknesses up to 7 μm were fabricated, and the performance of these RBL-free PSCs was assessed. Our results demonstrate that an RBL-free PSC with a thickness of 3 μm can achieve an efficiency approaching 13.83%. Notably, in these RBL-free PSCs, unlike conventional perovskite architectures, the thickness of the perovskite layer directly influences the recombination pathway, consequently leading to an increase in the open-circuit voltage. These findings highlight the importance of RBL-free thick-film PSCs and suggest their significant potential for the development of high-performance devices.