Photoluminescence Enhancement Effect of CsPbBr3 Quantum Dots Modified by Differently Reduced Graphene Oxide for QLED Devices

This work systematically investigates the optical behaviors of cesium lead bromide perovskite quantum dots (CsPbBr3 PeQDs) functionalized with reduced graphene oxide (RGO) at varying reduction levels, and further explores their feasibility as emissive layers (EMLs) in quantum dot light-emitting diodes (QLEDs). Four batches of RGO with tunable reduction degrees were synthesized by adjusting the amounts of ammonia solution and hydrazine hydrate added, followed by the fabrication of RGO@CsPbBr3 hybrids via an in situ hot-injection method. Experimental characterizations reveal that the photoluminescence quantum yield (PLQY) of the as-prepared RGO@CsPbBr3 composites can be precisely modulated from 45% to 65% by tuning the reduction degree of RGO. Using the optimized RGO@CsPbBr3 sample, multilayer QLEDs with the architecture of indium tin oxide (ITO)/PEDOT:PSS/Poly-TPD/TAPC/RGO@CsPbBr3/TPBi/Al were fabricated. Electroluminescence (EL) measurements show that the optimized device exhibits a turn-on voltage of approximately 3 V and a characteristic emission peak at 513 nm. Compared with devices based solely on bare CsPbBr3 PeQDs, the composite-based QLED displays a slight blue shift in emission wavelength and enhanced electroluminescence intensity, which is attributed to the localized surface plasmon resonance effect induced by the RGO nanosheets. This work presents a reliable strategy to optimize perovskite hybrid optics for light-emitting applications.