Spray pyrolysis-deposited NiO film as a hole-injection layer for CsPbBr3 nanocrystal-based light-emitting diodes

Abstract

In perovskite-based light-emitting diodes (LEDs), employing an inorganic material for the hole-injection layer instead of an organic material is crucial for attaining optimal performance and device stability. This layer needs to exhibit [Formula: see text]-type conductivity with high carrier mobility while being fabricated with a simple and industrially compatible method. In this study, uniform and thin [Formula: see text]-type NiO films were deposited through spray pyrolysis in an air atmosphere. The as-deposited film showed poor crystallinity, and high resistance reduced hole-injection performance. Subsequent thermal treatment at 500∘C enhanced the crystallinity of the layer, reducing resistance and improving LED performance. The film exhibited [Formula: see text]-type semiconductor characteristics, and its carrier mobility, carrier concentration and resistivity were 53.0 × 10[Formula: see text] cm3, 116 cm2 ⋅ Vs[Formula: see text] and 0.98 [Formula: see text] ⋅ cm[Formula: see text], respectively. Moreover, a compact CsPbBr3 nanocrystal (NC) film as an emitting layer was deposited with a centrifugal coating technique. The resulting LED component featuring a fluoride-doped tin oxide (FTO)/NiO/CsPbBr3 NCs/tris-(1-phenyl-1H-benzimidazole)/LiF/Au structure and demonstrating high luminance, current efficiency and external quantum efficiency (EQE) reached 12,000 cd ⋅ m[Formula: see text], 8.8 cd ⋅ A[Formula: see text] and 3.56%, respectively, at 5.5 V. Our work offers a simple and unique approach for accelerating the development of advanced interfacial materials and circumventing major interfacial problems in solution-processed perovskite NC films for high-performance LEDs.