Thermal stability enhancement in perovskite solar cells using W-doped ZnO/single crystalline anatase TiO₂ nanoparticle bilayer

Abstract The interface between the electron transport layer (ETL) and the perovskite layer is essential for fabricating efficient and stable perovskite solar cells (PSCs). In this study, we introduced a bilayer ETL of W-doped ZnO and single crystalline anatase TiO 2 nanoparticles (average diameter = 6–10 nm) to mitigate the degradation between W-doped ZnO ETL and MA-containing perovskite layer. After 12 h of annealing at 85 °C, the perovskite grown on the bilayer exhibited strong perovskite peaks, indicating a significant slowdown in decomposition. Moreover, the bilayer device demonstrated superior thermal stability, retaining over 60% of their initial power conversion efficiency (PCE) after 24 h of annealing, while the W-doped ZnO single-layer device lost all efficiency. PSCs with the W-doped ZnO/Anatase TiO 2 bilayer achieved PCE of 16.63%, compared to 11.88% for the W-doped ZnO single layer. This bilayer application offers a promising pathway for improving both the efficiency and stability for perovskite-based optoelectronic devices.