Publication date: 3rd July 2020
Solid-state lighting is currently based on light down-conversion from blue emitting InGaN LEDs to yellow or green-red emitting phosphors. Such structures suffer from relatively poor light conversion efficiency, color purity and operational frequency limited by the phosphor emission characteristics. Lead halide perovskite nanocrystals (LHP NCs) offer the prospect of higher emission quantum yield with narrower PL linewidth and spectral tunability across the visible via facile ion exchange reactions, making them promising alternatives to phosphors for lighting applications.
Herein, we demonstrate efficient light down-conversion mediated by Förster Resonant Energy Transfer (FRET) in InGaN/GaN multiple quantum well (MQW) nanohole arrays, coated with green emitting CsPbBr3 and FAPbBr3 NC and red emitting FAPbI3 NC overlayers. FRET is a near-field coupling process that is highly sensitive to the separation of the interacting excitons. Patterning the InGaN MQW into nanohole arrays allows a minimum nitride-NC separation while increasing the heterointerfacial area, thus improving simultaneously the non-radiative and radiative transfer efficiency. Detailed steady state and time-resolved photoluminescence (PL) studies indicate a significant reduction in the MQW PL decay time in the presence of the LHP NCs, accompanied by a significant concurrent increase of the integrated emission of the nanocrystals, providing evidence of efficient light down-conversion mediated by FRET with efficiencies as high as 80%.
The work was supported by Research & Innovation Foundation of Cyprus, under the "NEW STRATEGIC INFRASTRUCTURE UNITS-YOUNG SCIENTISTS" Program ("INFRASTRUCTURES/1216/0004"). M. Athanasiou acknowledges support by the University of Cyprus via the "ADVANCED POSTDOCTORAL RESEARCH FELLOWSHIPS 2018-2019” Program and by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 831690.