Tetrachromatic hybrid white light-emitting diodes and the energy transfer between conjugated polymers and CdSe/ZnS quantum dots

We demonstrate the fabrication and characterization of high efficacy tetrachromatic white light-emitting diodes based on polymer and colloidal quantum dots (QDs). With a certain amount of yellowish green-emitting 2,3-dibutoxy-1,4-poly(phenylene vinylene) (DBPPV) and red-emitting CdSe/ZnS QD composite attached to an InGaN blue chip, stable and pure white light with CIE-1931 chromaticity coordinates of (0.325, 0.342), a correlated color temperature of 5800 K, and a color rendering index of 75 can be obtained. The luminous flux and efficacy of the device operated at 20 mA are 0.55 lm and 330 lm/W, respectively. In this device configuration, the emission of QDs is due not only to the radiative energy transfer from InGaN QWs and DBPPV but also to the Förster energy transfer of excitons in adjacent DBPPV chains. Based on a theoretical calculation, a high efficiency up to 32% is possible.