Optoelectronic Interactions of WS₂-ZnO for Scalable LEDs Based on Two-Dimensional Materials

Recent advances in scalable large-area light-emitting diodes (LEDs) utilizing two-dimensional materials have spurred the investigation of promising architectures. Among the forefront LED architectures under investigation is the n-i-p design, featuring distinct layers comprising an electron-transport material (n), an intrinsic active material (i), and a hole-transport material (p). This framework facilitates efficient electron-hole recombination and subsequent light emission. Tungsten disulfide (WS₂) has attracted significant attention as an active material in such LEDs, given its direct bandgap, high stability, and robust photoluminescence (PL). Meanwhile, zinc oxide (ZnO), an n-type semiconductor, is under examination as a candidate for the electron-transport layer. This study investigates the interactions between WS₂ and both single-crystalline ZnO and spatial atomic layer deposition (SALD)-grown ZnO, with a primary focus on evaluating the optoelectronic interaction of this heterostructure. A comprehensive set of characterization techniques, including PL and Raman spectroscopy to probe optoelectronic properties, atomic force microscopy for morphological insights, Kelvin probe force microscopy for surface potential variations, and X-ray photoelectron spectroscopy to delve into chemical composition and electronic states at the WS₂-ZnO interface, is employed. Ultimately, this research aims to determine whether SALD-grown ZnO is a suitable candidate for integration into the n-i-p LED architecture, paving the way for scalable and efficient optoelectronic devices based on 2D materials.