Stable blue phosphorescent organic LEDs that use polariton-enhanced Purcell effects.

Phosphorescent organic light-emitting diodes (PHOLEDs) feature high efficiency, brightness and colour tunability suitable for both display and lighting applications. However, overcoming the short operational lifetime of blue PHOLEDs remains one of the most challenging high-value problems in the field of organic electronics. Their short lifetimes originate from the annihilation of high-energy, long-lived blue triplets that leads to molecular dissociation.

Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density.

Thermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m at an efficiency of 6.

Near-perfect photon utilization in an air-bridge thermophotovoltaic cell.

Thermophotovoltaic cells are similar to solar cells, but instead of converting solar radiation to electricity, they are designed to utilize locally radiated heat. Development of high-efficiency thermophotovoltaic cells has the potential to enable widespread applications in grid-scale thermal energy storage, direct solar energy conversion, distributed co-generation and waste heat scavenging. To reach high efficiencies, thermophotovoltaic cells must utilize the broad spectrum of a radiative thermal source.

From 2D to 3D: Strain- and elongation-free topological transformations of optoelectronic circuits.

Optoelectronic circuits in 3D shapes with large deformations can offer additional functionalities inaccessible to conventional planar electronics based on 2D geometries constrained by conventional photolithographic patterning processes. A light-sensing focal plane array (FPA) used in imagers is one example of a system that can benefit from fabrication on curved surfaces. By mimicking the hemispherical shape of the retina in the human eye, a hemispherical FPA provides a low-aberration image with a wide field of view.

Photoresponse of an Organic Semiconductor/Two-Dimensional Transition Metal Dichalcogenide Heterojunction.

We study the optoelectronic properties of a type-II heterojunction (HJ) comprising a monolayer of the transition metal dichalcogenide (TMDC), WS, and a thin film of the organic semiconductor, 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA). Both theoretical and experimental investigations of the HJ indicate that Frenkel states in the organic layer and two-dimensional Wannier-Mott states in the TMDC dissociate to form hybrid charge transfer excitons at the interface that subsequently dissociate into free charges that are collected at opposing electrodes. A photodiode employing the HJ achieves a peak external quantum efficiency of 1.