Nitrogen-Doped Graphene Quantum Dot–Tin Dioxide Nanocomposite Ultrathin Films as Efficient Electron Transport Layers for Planar Perovskite Solar Cells

Tin dioxide (SnO2) has recently been recognized as an excellent electron transport layer (ETL) for perovskite solar cells (PSCs) due to its advantageous properties, such high mobility, suitable energy band alignment, simple low-temperature process, and good chemical stability. In this work, nitrogen-doped graphene quantum dots (N-GQDs) were prepared using a hydrothermal method then used fabricate N-GQD:SnO2 nanocomposite ultrathin films. films investigated applied layers in planar PSCs. The presence of N-GQDs with average size 6.2 nm the improved morphology reduced surface defects. excitation–emission contour map indicated that exhibited remarkably enhanced light-harvesting capability possibility absorbing UV light producing emissions visible range. quenching photoluminescence spectra showed extraction charge recombination. As result, power conversion efficiency (PCE) our PSCs fabricated optimized was by 20.4% over pristine SnO2-based devices.