Nanocrystal-based light-emitting diodes utilizing high-efficiency nonradiative energy transfer for color conversion

We report a practical implementation of high-efficiency color conversion in an electrically pumped light-emitting diode (LED) using nonradiative energy transfer. On the basis of a new LED design that offers both strong energy-transfer coupling and efficient carrier injection, we show that a hybrid structure comprising a single monolayer of CdSe nanocrystals assembled on top of an InGaN/GaN quantum well provides nearly 10% color conversion efficiency. This value is significantly higher than that for a traditional absorption-re-emission color-conversion scheme in a similar device structure. Furthermore, these hybrid devices can also provide improved efficiencies, compared not only to phosphor-based structures but also to stand-alone LEDs.