Project description
The future is very bright for organic LEDs
Light-emitting diodes (LEDs) have revolutionised lighting, sensing and communications applications from televisions and signage to biomedicine. It took a while, though. More than a century ago, scientists discovered that a silicon carbide crystal emitted a yellowish light when voltage was applied to it. LEDs became widely available commercially in the 1970s. Now, thin-film organic alternatives to semiconductor materials, called organic LEDs (OLEDs), are gaining ground. However, despite their many benefits relative to conventional LEDs, they are limited significantly in their brightness. Further, they cannot be easily used as a laser medium due to technical challenges with pumping, the process by which energy is supplied to the medium to raise its electrons to an excited state. ULTRA-LUX will address both these challenges to deliver the first ultra-bright, thin-film light-emitting device and a thin-film injection laser to complement it.
Objective
Thin-film light sources such as OLEDs are extremely valuable, as, in contrast to III-V crystalline LEDs, they can be precisely designed and dimensioned, as single components or in massive arrays, into any target application without the need of hetero-assembly. Unfortunately, their light power density remains about 300 times smaller than that of III-V LEDs. Also, none of today’s thin-film light sources could ever be brought to lasing by electrical pumping.
It is the objective of this project to break through the barriers that limit the brightness of thin-film light sources and to achieve lasing by electrical pumping (“injection lasing”) in such sources.
Our first target is to create a high-brightness (30W/cm2) thin-film light-emitting device. For the emission layer, we propose a perovskite semiconductor with controlled quantum-confinement features (wells or dots). It will be integrated into a novel light-emitting device, in which electron and hole injection are separately controlled by gates, such that a perfect charge balance is achieved up to the highest current densities.
Our next target is to create a thin-film injection laser. We present several innovative strategies to lower the lasing threshold. The emission layer of our light-emitting device will be shaped as a ring resonator with ultra-low optical losses. The gates will be patterned to spatially modulate the carrier injection in the emission layer, which will efficiently restrict the pumping to few selected modes. Further elaborations of cavity designs can lead to mode-locking. Combined with the efficiency of the quantum-confined perovskite emission layer in producing optical gain, these features will reduce the lasing threshold current density to below 100 A/cm2, within reach of our thin-film device.
These novel devices will serve numerous applications in the fields of sensing and ICT, by enabling massive optical interconnects, augmented reality displays, on-chip sensing and more.
Fields of science
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Funding Scheme
ERC-ADG - Advanced GrantHost institution
3001 Leuven
Belgium