White electroluminescence from a poly(N-vinylcarbazole) layer doped with CdSe/CdS core–shell quantum dots

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Abstract
Hybrid organic/inorganic white light-emitting diodes (LEDs) were fabricated of semiconductor polymer poly(N-vinylcarbazole) (PVK) doped with CdSe/CdS core–shell semiconductor quantum dots (QDs). The device, with a structure of indium–tin-oxide (ITO)|3,4-polyethylene–dioxythiophene–polystyrene sulfonate (PEDOT:PSS)|PVK:CdSe/CdS|Al, emitted a pure white light spanning the whole visible region from 400 to 800 nm. The Commission Internationale del'Eclairage coordinates (CIE) remained at x = 0.33,y = 0.34 at wide applied voltages. The maximum brightness and electroluminescence (EL) efficiency reached 180 cd m−2 at 19 V and 0.21 cd A−1 at current density of 2 mA cm−2, respectively. The realization of the pure white light emission is attributed to the incomplete energy and charge transfer from PVK to CdSe/CdS core–shell QDs.