The use of blue filters to bypass the slow yellow response of the phosphors severely impacts the usable signal integrity.
Working on removing the inefficiencies and technical limitations of phosphor-based white lights, a team of researchers from the University of Sheffield has designed a novel type of white LED by closely hybridizing an inorganic InGaN/GaN blue LED with pockets of organic light-emitting polymers (OLEPs).
The idea behind this hybridization is to leverage the OLEDs' much faster response time together with a highly efficient near-field non-radiative Förster resonance energy transfer (FRET) between the inorganic active region and the nearby yellow-emitting organic polymer.
It is understood that nonradiative FRET involves a near-field radiation-less energy transfer from inorganic active-regions (donors) to OLEPs (acceptors) through dipole−dipole Coulombic interactions, hence the need to minimize the separation between donor and acceptor dipoles so they can interact.
The researchers started with a commercial blue InGaN/GaN LED wafer grown on c-plane sapphire, with a 160nm thick InGaN/GaN MQW active region.
In a paper titled "Electrically Injected Hybrid Organic/Inorganic III-Nitride White LightEmitting Diodes with Nonradiative Förster Resonance Energy Transfer" published in ACS Photonics, they detail how they patterned a two-dimensional microhole array structure deep across the MQW active region to drop cast a yellow-emitting polyfluorene copolymer.