Hybrid White Light-Emitting Diodes Utilizing Radiative or Nonradiative Energy Transfer for Wavelength Conversion

摘要

Hybrid light-emitting diodes (LEDs) were fabricated by spin coating poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) on blue InGaN/GaN multiple-quantum-well (MQW) LED chips as a downconverter. As the F8BT film thickness was in the range of 235-290 nm, the hybrid LEDs emitted cool white light with a downconversion efficiency of 28.8. The F8BT film quality was markedly improved by postannealing at 200 °C, raising the down-conversion efficiency to 82.6. To obtain more efficient white light emission, we proposed to insert Ag nanoparticles (NPs) with a diameter of 13 nm at the inorganic-organic interface to form an MQWs/NPs/F8BT structure. Simulations showed that nonradiative energy transfer from the MQWs to F8BT can be mediated by localized surface plasmons, leading to more efficient downconversion and overall white light emission. The proof of concept of such a hybrid LED will pave the way toward high-performance phosphor-free white LED sources for microdisplay and general lighting applications.