Effect of sulfur-doped graphene quantum dots incorporation on morphological, optical and electron transport properties of CH₃NH₃PbBr₃ perovskite thin films

Organic–inorganic hybrid perovskite materials have recently attracted extensive interest to develop next-generation high efficiency optoelectronic devices. However, in many of these devices, perovskite thin films are the key source of photogenerated electron and hole pairs. Therefore, a strategy for the preparation of high-quality perovskite thin films with a fewer number of traps at surfaces and grain boundaries is highly desired. In this work, sulfur-doped graphene quantum dots (S-GQDs) were synthesized and incorporated in the CH₃NH₃PbBr₃ perovskite precursor to prepare S-GQDs incorporated perovskite thin films. The as-prepared thin films were systematically characterized using X-ray diffractometer, field emission scanning electron microscope, UV–Vis and fluorescence spectrophotometer to investigate the effect of different amounts of S-GQDs on their morphology, optical absorbance and electron transfer properties. The experimental findings revealed that multiple surface functional groups, quantum confinement and desirable electronic conductivity in S-GQDs help passivate the perovskite surface by reducing the surface and grain boundary traps. Interestingly, the incorporation of S-GQDs increased the light absorption of CH₃NH₃PbBr₃ along with faster electron transfer across their interfaces. Hence, this strategy of S-GQDs incorporation presents a versatile and novel way to prepare highly efficient perovskite thin films for developing next-generation solar cells, light emitting diodes and other optoelectronic devices.