Unraveling the Energy Transfer Mechanisms in Bi-Color and Tri-Color Quantum Dots: toward Efficient White Quantum Dot Light-Emitting Diodes

摘要

One of the considerable effects that limit the performance of white quantumdot (QD) light-emitting diodes (W-QLEDs) is the F?rster resonance energytransfer (FRET) among different colored QDs. Here, the FRET mechanismsamong QDs are unraveled and how FRET affects the performance ofW-QLEDs is disclosed. The results show that although FRET is beneficial forharvesting the energy of nonradiative excitons, it is unhelpful for the improvementof the total emission quantum yield of bi-color or tri-color QDs. Dueto the existence of FRET, a large proportion of blue QDs should be incorporatedto obtain a balanced white emission, which remarkably deterioratesthe efficiency of the white emission. With the developed device structure, theFRET among QDs can be suppressed, and thus, the external quantum efficiency(power efficiency) of the W-QLEDs is improved from 9.31% to 27.03%(12.18–25.52 lm W~(?1)), representing an improvement factor of 2.9 (2.1) comparedwith that of the conventional W-QLEDs. The results not only deepenthe insight into the FRET mechanisms among QDs but also provide solutionsand inspirations for the future development of efficient W-QLEDs.