Sn Composition Engineering Toward the Breakthrough of Transparent Front Electrodes for Efficient and Stable Perovskite Solar Cells

Abstract To overcome the Shockley–Queisser limit, studies have focused on improving the efficiency of perovskite solar cells (PSCs) through several optimization and tandem‐structure design strategies. Furthermore, the significance of emerging transparent front electrodes (TFEs), which exert a direct and substantial influence on the performance of PSCs, is on the rise. Therefore, further research must be conducted to validate these effects in improving the existing performance of PSCs. Thus, this study developed a composition‐engineered indium tin oxide (CE‐ITO) TFE that outperforms commercial ITO (C‐ITO; 10 at.% Sn doped ITO) for efficient and stable PSCs. The CE‐ITO electrode (7.50 at.% Sn doped ITO) has a large columnar structure and good thermal stability, which are ideal for high‐performance PSCs. Compared to C‐ITO, CE‐ITO has a smoother surface, higher conductivity, lower resistivity, and improved optical transmittance in the active layer. These contribute to the larger perovskite active‐ and electron‐transport layers, less active‐layer degradation, and lower shunt resistance. The various merits of CE‐ITO enable high‐performance PSCs with a maximum power conversion efficiency of 23.35% and long‐term stability by simply substituting C‐ITO with optimal CE‐ITO.