Electroluminescence from CdSe quantum-dot/polymer composites

Electroluminescence is obtained from nearly monodisperse CdSe nanocrystallites (quantum dots) incorporated into thin films (1000 Å) of polyvinylcarbazole (PVK) and an oxadiazole derivative (t-Bu-PBD) and sandwiched between ITO and Al electrodes. The electroluminescence and photoluminescence spectra (bandwidths ≤40 nm) are nearly identical at room temperature and are tunable from ∼530 to ∼650 nm by varying the size of the dots. Voltage studies at 77 K indicate that while only the dots electroluminesce at the lower voltages, both the dots and the PVK matrix electroluminesce at higher applied voltages. Variable temperature studies indicate that the electroluminescence efficiency increases substantially as the films are cooled down to cryogenic temperatures.