Highly polarized electrically driven single-photon emission from a non-polar InGaN quantum dot

APPLIED PHYSICS LETTERS 111:25 (2017) ARTN 251108

Authors:

CC Kocher, TJ Puchtler, JC Jarman, T Zhu, T Wang, L Nuttall, RA Oliver, RA Taylor

Temperature induced crossing in the optical bandgap of mono and bilayer MoS2 on SiO2.

Scientific reports 8:1 (2018) 5380-5380

Authors:

Y Park, CCS Chan, RA Taylor, Y Kim, N Kim, Y Jo, SW Lee, W Yang, H Im, G Lee

Abstract:

Photoluminescence measurements in mono- and bilayer-MoS2 on SiO2 were undertaken to determine the thermal effect of the MoS2/SiO2 interface on the optical bandgap. The energy and intensity of the photoluminescence from monolayer MoS2 were lower and weaker than those from bilayer MoS2 at low temperatures, whilst the opposite was true at high temperatures above 200 K. Density functional theory calculations suggest that the observed optical bandgap crossover is caused by a weaker substrate coupling to the bilayer than to the monolayer.

Harvesting electrical energy using plasmon-enhanced light pressure in a platinum cut cone

Optics Express 29:22 (2021) 35161-35171

Authors:

HY Lee, MS Kwak, KW Lim, HS Ahn, GT Hwang, DH Ha, RA Taylor, SN Yi

Abstract:

We have designed a method of harvesting electrical energy using plasmon-enhanced light pressure. A device was fabricated as a cut cone structure that optimizes light collection so that the weak incident light pressure can be sufficiently enhanced inside the cut cone to generate electrical energy. An increase in the device’s current output is a strong indication that the pressure of incident light has been enhanced by the surface plasmons on a platinum layer inside the cut cone. The electrical energy harvested in a few minutes by irradiating pulsed laser light on a single micro device was possible to illuminate a blue LED.

Resonantly Pumped Bright-Triplet Exciton Lasing in Cesium Lead Bromide Perovskites.

ACS photonics 8:9 (2021) 2699-2704

Authors:

Guanhua Ying, Tristan Farrow, Atanu Jana, Hanbo Shao, Hyunsik Im, Vitaly Osokin, Seung Bin Baek, Mutibah Alanazi, Sanjit Karmakar, Manas Mukherjee, Youngsin Park, Robert A Taylor

Abstract:

The surprising recent observation of highly emissive triplet-states in lead halide perovskites accounts for their orders-of-magnitude brighter optical signals and high quantum efficiencies compared to other semiconductors. This makes them attractive for future optoelectronic applications, especially in bright low-threshold nanolasers. While nonresonantly pumped lasing from all-inorganic lead-halide perovskites is now well-established as an attractive pathway to scalable low-power laser sources for nano-optoelectronics, here we showcase a resonant optical pumping scheme on a fast triplet-state in CsPbBr<sub>3</sub> nanocrystals. The scheme allows us to realize a polarized triplet-laser source that dramatically enhances the coherent signal by 1 order of magnitude while suppressing noncoherent contributions. The result is a source with highly attractive technological characteristics, including a bright and polarized signal and a high stimulated-to-spontaneous emission signal contrast that can be filtered to enhance spectral purity. The emission is generated by pumping selectively on a weakly confined excitonic state with a Bohr radius ∼10 nm in the nanocrystals. The exciton fine-structure is revealed by the energy-splitting resulting from confinement in nanocrystals with tetragonal symmetry. We use a linear polarizer to resolve 2-fold nondegenerate sublevels in the triplet exciton and use photoluminescence excitation spectroscopy to determine the energy of the state before pumping it resonantly.

An insight study into the parameters altering the emission of a covalent triazine framework

Journal of Materials Chemistry C Materials for optical and electronic devices Royal Society of Chemistry (2021)

Authors:

Panagiota Bika, Vitaly Osokin, Tatiana Giannakopoulou, Nadia Todorova, Mo Li, Andreas Kaidatzis, Robert A Taylor, Christos Trapalis, Panagiotis Dallas

Abstract:

Covalent triazine frameworks (CTFs) synthesized through nucleophilic substitution of 4,4’ bipyridine on the carbon atoms of cyanuric chloride were studied as fluorescent sensors. The band gap of the materials was calculated to be 2.95 eV from diffuse reflectance measurements, while from the adsorption in aqueous dispersions, we obtained the value of 3.7 eV. A partial exfoliation of the layered CTFs in water or tetrahydrofuran led to different morphologies, increased emission lifetime and fluorescence quantum yield. The pattern of their light emission properties in combination with their redox states was defined with the addition of a series of acidic and basic analytes. Another unique aspect of these semiconducting materials is the induced aggregation and the subsequent enhancement of emission under ultraviolet illumination.