Highly Efficient and Stable Perovskite Solar Cells via a Multifunctional Curcumin-Modified Buried Interface

The buried interface between the electron transport layer and the perovskite layer suffers from severe interface defects and imperfect energy level alignment. To address this issue, this study employs a multifunctional organic molecule, curcumin, to modify the interface between SnO2 and the perovskite layer. The curcumin effectively passivates the defects on both sides of the interface, reducing −OH and oxygen vacancy defects on the SnO2 surface and passivating uncoordinated Pb2+ in the perovskite layer. Through density functional theory calculations, it was found that CM modification at the buried interface increased the defect formation energies of deep (VPb and PbI) and shallow (VI) defects at the bottom of the perovskite film. This results in a more compatible energy level alignment and lower defect density at the interface, enhancing carrier transport across it. Consequently, the devices based on curcumin achieve an impressive champion power conversion efficiency (PCE) of 24.46%, compared to 22.03% for control devices. The device retains 90.42% of its initial PCE after 1000 h at 25 °C and 50 ± 5% relative humidity. This work demonstrates a green, hydrophobic, and efficient molecular modification method for the buried interface, laying the foundation for the development of high-performance and stable perovskite solar cells.