Computational and Experimental Investigations of Mg‐Doped SnO ₂ Electron Transport Layer for Indoor Perovskite Solar Cells

ABSTRACT Tin oxide (SnO ₂ ) has been widely used as an electron transport layer (ETL) in perovskite solar cells (PSCs) due to the excellent charge transport properties. In this work, we present a comprehensive computational and experimental investigation of a low‐temperature strategy for developing Mg‐doped SnO ₂ (Mg‐SnO ₂ ) as an ETL to enhance the performance of indoor perovskite solar cells (i‐PSCs). Experimental results demonstrate that Mg incorporation enhances optical transparency, increases the bandgap, and improves charge transport by reducing charge recombination at the ETL/perovskite interface. These enhancements lead to superior PCEs, achieving 35.54% under indoor LED illumination and 20.28% under standard one sun conditions, significantly outperforming undoped SnO ₂ ‐based devices. Complementary density functional theory (DFT) simulations support the experimental findings, revealing that Mg doping decreases deep trap states, and contribute to improved ETL conductivity. The strong correlation between theoretical predictions and experimental outcomes underscores the effectiveness of Mg‐SnO ₂ as a high‐performance and stable ETL for indoor photovoltaic applications. This study establishes a practical pathway for developing optimized Mg‐doped electron transport layer for efficient indoor light harvesting.