Efficient solution-processed hybrid polymer-nanocrystal near infrared light-emitting devices

We report solution-processed hybrid LEDs, emitting infrared light with enhanced efficiency, based on PbSe nanocrystal (NC) lumophores embedded a conjugated polymer forming the nanocomposite active layer. The effect of device geometry and the NC-polymer blend composition on device performance is Studied in detail. Increasing the PbSe NC concentration leads to a substantial decrease in device current, and an increase in efficiency and turn-on voltage. Analysis of the device data indicates that the PbSe NCs act as carrier traps and radiative recombination centers. With optimized concentration of NC emitters and active layer thickness, the devices exhibit an external electroluminescence quantum efficiency of 0.83% at a peak emission wavelength of 1280 nm. (C) 2009 Elsevier B.V. All rights reserved.