New light from hybrid inorganic–organic emitters

Abstract

We present the highlights of a research programme on hybrid inorganic-organic light emitters. These devices combine recent developments in III-V nitride technology (including UV emitting micro-arrays and specifically tailored quantum wells) with conjugated polymers to access the entire visible spectrum. Two types of devices are studied, those based on down conversion of the quantum well emission by radiative transfer and those based on non-radiative resonant energy transfer. The spectral and operating characteristics of the devices are described in detail. Selectable colour micro-arrays and bar emitters are demonstrated. The nature of the non-radiative energy transfer process has also been studied and we find transfer efficiencies of up to 43% at 15 K, with a 1/R 2 dependence on the distance between quantum well and polymer layer, suggesting a plane-plane interaction. The relative importance of the non-radiative resonant energy transfer process increases with temperature to be up to 20 times more efficient, at 300 K, than the radiative transfer process.

Dependence of Resonance Energy Transfer on Exciton Dimensionality

“…However, a blend of appropriately chosen fluorescent polymers, or quantum dots (QDs), yields multiple emission bands in the visible. They can be employed as highly efficient phosphors on UV or blueemitting quantum well (QW) light-emitting diodes based on III-nitride materials and offer an alternative to rare earth based phosphors, which are becoming increasingly scarce [2]. In such hybrid configurations, resonance energy transfer (RET) can overcome limitations for charge injection and transport in semiconducting polymers or QDs [3].…”

Carrier density dependence of plasmon-enhanced nonradiative energy transfer in a hybrid quantum well-quantum dot structure

“…Both options introduce additional fabrication complexity for commercial devices. Nonradiative energy transfer from QWs to light emitting polymers has also been theoretically and experimentally investigated with a view to color conversion applications [12][13][14][15][16][17]. Again, the need to minimise the separation between the QW donor and organic acceptor is a critical issue for commercial device fabrication.…”

Fabrication of planar GaN-based micro-pixel light emitting diode arrays

“…Consequently, this process requires a lower number of fabrication steps than previously used processes using mesa etching for pixel definition and dielectric deposition for electrical insulation [2]. It leads to a planar active area well suited for further integration of functional micro-elements, including microfluidic-channels, microoptics or luminescent materials for colour conversion [3,4]. This new fabrication route has been validated by fabricating and characterizing an individually addressable micro-stripe LED array emitting at 470 nm.…”