Toward near-white electroluminescence with enhanced blue emission from carbon dots in PEDOT:PSS/ZnO organic/inorganic hybrid heterojunctions

Abstract

White light-emitting diodes (WLEDs) produced by using carbon dots (CDs) and related materials are of great interest for their huge potential in backlight and solid-state lighting applications. Besides the tremendous efforts to use CDs as phosphors of GaN-based blue or UV LED chips to produce photoluminescent WLEDs, it is really not easy to produce electroluminescent WLEDs with CDs as the active layer owing to the complex emission mechanism of the CDs. Here, by combining the merits of both the blue emissive CDs and ZnO nanowires (NWs), near-white electroluminescence (EL) is demonstrated by enhancing blue emission from the blue CDs and with the help of a thin PMMA polymer layer for the PEDOT:PSS/ZnO NWs organic/inorganic hybrid heterojunction LEDs. By interfacial modification with the thin PMMA layer, EL intensity of the device is boosted strikingly (especially for the blue emission from CDs and ZnO NWs), making the emission color of the device tune from yellowish green toward near white. The findings in this work may pave a feasible way to realize CDs-based electroluminescent WLEDs and give a practical demonstration to regulate the blue emission of ZnO to produce WLEDs.