Aged sol-gel solution-processed texture tin oxide for high-efficient perovskite solar cells

Mesoporous n-i-p perovskite solar cells (PeSCs) demonstrate attractive potential for obtaining high power conversion efficiencies (PCEs), by employing inorganic electron transport layers (ETLs). However, these ETLs composed of dual layers (a condense layer and a mesoporous layer) suffer the composite process and high sintering temperature. Here, we demonstrate a simple and efficient process to improve the device performance of PeSCs by using a textured SnO2 film. Self-aged sol-gel SnO2 solution after spin coating results in a textured structure without sacrificing the surface coverage. Excellent light trapping ability is achieved by optimizing the aged time of sol-gel SnO2 solution, which mimics the evolution of the conventional mesoporous layer. Such a SnO2 textured structure provides a large contact area for rapid charge extraction, and alleviates interfacial recombination loss. Therefore, this PeSC yields an optimal PCE of 19%, which is prominent in state-of-the-art SnO2-based devices. These results indicate that one-step solution processed SnO2 with a textured structure offers a simple and efficient way to improve the device performance of PeSCs without a complex process.