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Perovskite quantum dots (QDs) have showed excellent optoelectronic properties to extend the application range of novel solid-state lighting, such as perovskite QD based LEDs (QD-LEDs). However, the traditional device structure of perovskite QD-LEDs employed PEDOT:PSS as a hole inject layer (HIL), which impairs stability due to acidic surface characteristics. This study proposes the sputtered NiO films as an HIL to replace acidic PEDOT:PSS. The NiO films with significantly different characteristics were prepared by controlling the sputtering parameters to investigate the devices’ performance of NiO-based CsPbBr3 QD-LEDs. The optimized device showed an excellent performance with maxima luminescence of 20,118 cd/m2 and an external quantum efficiency (EQE) up to 3.63%.

In this study, the effect of radical intensity on the deposition mechanism, optical, and electrical properties of tin oxide (SnO2) thin films is investigated. The SnO2 thin films are prepared by plasma-enhanced atomic layer deposition with different plasma power from 1000 to 3000 W. The experimental results show that plasma contains different amount of argon radicals (Ar*) and oxygen radicals (O*) with the increased power. The three deposition mechanisms are indicated by the variation of Ar* and O* intensities evidenced by optical emission spectroscopy. The adequate intensities of Ar* and O* are obtained by the power of 1500 W, inducing the highest oxygen vacancies (OV) ratio, the narrowest band gap, and the densest film structure. The refractive index and optical loss increase with the plasma power, possibly owing to the increased film density. According to the Hall effect measurement results, the improved plasma power from 1000 to 1500 W enhances the carrier concentration due to the enlargement of OV ratio, while the plasma powers higher than 1500 W further cause the removal of OV and the significant bombardment from Ar*, leading to the increase of resistivity.

The theoretical mechanism of open-circuit voltages (VOC) in OSCs based on various small molecule organic materials is studied. The structure under investigation is simple planar heterojunction (PHJ) by thermal vacuum evaporation deposition. The various wide band gaps of small molecule organic materials are used to enhance the power conversion efficiency (PCE). The donor materials used in the device include: Alpha-sexithiophene (α-6T), Copper(II) phthalocyanine (CuPc), boron subnaphthalocyanine chloride (SubNc) and boron Subphthalocyanine chloride (SubPc). It is combined with fullerene or SubPc acceptor material to obtain a comprehensive understanding of the charge transport behavior. It is found that the VOC of the device is largely limited by charge transport. This was associated with the space charge effects and hole accumulation. These results are attributed to the improvement of surface roughness and work function after molybdenum trioxide (MoO3) is inserted as an anode buffer layer.