A5017020142- GaN-based semiconductor devices and materials
- Perovskite Materials and Applications
- Quantum Dots Synthesis And Properties
- Ga2O3 and related materials
- ZnO doping and properties
- Photonic and Optical Devices
- Nanowire Synthesis and Applications
- Optical properties and cooling technologies in crystalline materials
- Organic Light-Emitting Diodes Research
- Semiconductor Quantum Structures and Devices
- Optical Coatings and Gratings
- Solid-state spectroscopy and crystallography
- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Photonic Crystals and Applications
- Crystallization and Solubility Studies
- Plasmonic and Surface Plasmon Research
- Acoustic Wave Resonator Technologies
- Luminescence Properties of Advanced Materials
- Advanced Photocatalysis Techniques
- Thin-Film Transistor Technologies
- X-ray Diffraction in Crystallography
- Solid State Laser Technologies
- Lanthanide and Transition Metal Complexes
- Neural Networks and Reservoir Computing
University of Cyprus
2020-2024
University of Sheffield
2013-2020
Nanocrystal superlattices (NC SLs) have long been sought as promising metamaterials, with nanoscale-engineered properties arising from collective and synergistic effects among the constituent building blocks. Lead halide perovskite (LHP) NCs come across outstanding candidates for SL design, they demonstrate light emission, known superfluorescence, in single- multicomponent SLs. Thus far, LHP only assembled single-component SLs or coassembled dielectric NC blocks acting solely spacers between...
Nanocrystal (NC) self-assembly is a versatile platform for materials engineering at the mesoscale. The NC shape anisotropy leads to structures not observed with spherical NCs. This work presents broad structural diversity in multicomponent, long-range ordered superlattices (SLs) comprising highly luminescent cubic CsPbBr3 NCs (and FAPbBr3 NCs) coassembled spherical, truncated cuboid, and disk-shaped building blocks. nanocubes combined Fe3O4 or NaGdF4 spheres cuboid PbS form binary SLs of six...
Optically pumped green lasing with an ultra low threshold has been achieved using InGaN/GaN based micro-disk undercut structure on silicon substrates. The micro-disks a diameter of around 1 μm were fabricated by means combination cost-effective silica micro-sphere approach, dry-etching and subsequent chemical etching. these techniques both minimises the roughness sidewalls also produces excellent circular geometry. Utilizing this fabrication process, at room temperature under optical pumping...
The 1:1:1 reaction of DyCl3·6H2O, K3[Co(CN)6] and bpyO2 in H2O has provided access to a complex with formula [DyCo(CN)6(bpyO2)2(H2O)3]·4H2O (1) very good yield, while [DyFe(CN)6(bpyO2)2 (H2O)3]·4H2O (2) was also precipitated (also high yield) using K3[Fe(CN)6] instead K3[Co(CN)6]. Their structures have been determined by single-crystal X-ray crystallography characterized based on elemental analyses IR spectra. Combined direct current (dc) alternating (ac) magnetic susceptibility revealed...
Solution-processed lasers are cost-effective, compatible with a vast range of photonic resonators, and suited for mass production flexible, lightweight, disposable devices. The emerging class lead halide perovskite nanocrystals (LHP NCs) can serve as highly suitable active medium such lasers, owing to their outstanding optical gain properties the suppressed nonradiative recombination losses stemming from defect-tolerant nature. In this work, CsPbBr3 NCs embedded within polymeric Bragg...
The primary obstacle to the use of lead halide perovskite nanocrystals (NCs) in optoelectronics is inability traditional ligand engineering approaches provide robust surface passivation. structural lability can be mitigated by employing different ligands such as long-chain quaternary ammonium and zwitterionic surfactants. Here, we report a comprehensive study that probes impact passivation routes on optoelectronic properties weakly confined CsPbBr3 NCs. Spectroscopy unravels clear...
Lead halide perovskite nanocrystals (NCs) are highly suitable active media for solution-processed lasers in the visible spectrum, owing to wide tunability of their emission from blue red via facile ion-exchange reactions. Their outstanding optical gain properties and suppressed nonradiative recombination losses stem defect-tolerant nature. In this work, we demonstrate flexible waveguides combining transparent, bioplastic, polymer cellulose acetate with green CsPbBr3 or red-emitting...
Abstract In this study, 3 H ‐phenothiazin‐3‐one is identified as a photocatalyst for the photochemical oxidation of sulfides to sulfoxides. This photocatalytic method uses low catalyst loading (0.05 mol%), molecular oxygen sole oxidant, and blue LED lamp irradiation source. It can be applied both alkyl‐aryl alkyl‐alkyl sulfides. Moreover, also applicable in synthesis known pharmaceutically active compounds Modafinil Sulforaphane.
We demonstrate InGaN/GaN multi-quantum-well solar cells with nanostructures operating at a wavelength of 520 nm. Nanostructures periodic nanorod or nanohole array are fabricated by means modified nanosphere lithography. Under 1 sun air-mass 1.5 global spectrum illumination, fill factor 50 and an open circuit voltage 1.9 V achieved in spite very high indium content InGaN alloys usually causing degradation crystal quality. Both the significantly improve performance cells, while larger...
By means of time-resolved photoluminescence (PL) and confocal PL measurements, temporally spatially resolved optical properties have been investigated on a number InxGa1−xN/GaN multiple-quantum-well (MQW) structures with wide range indium content alloys from 13% to 35% (112¯2) semi-polar GaN high crystal quality, obtained through overgrowth nanorod templates. With increasing content, the radiative recombination lifetime initially increases as expected, but decreases if further 35%,...
Abstract An optically pumped multi-color laser has been achieved using an InGaN/GaN based micro-disk with undercut structure on a silicon substrate. The fabricated by means of combination cost-effective microsphere lithography technique and subsequent dry/wet etching processes. microdisk is approximately 1 μm in diameter. was designed such way that the vertical components whispering gallery (WG) modes formed can be effectively suppressed. Consequently, three clean lasing peaks at 442 nm, 493...
Microcavities based on group-III nitride material offer a notable platform for the investigation of light-matter interactions as well development devices such high efficiency light emitting diodes (LEDs) and low-threshold nanolasers.Disk or tube geometries in particular are attractive lasing applications due to their ability support finesse whispering gallery modes (WGMs) small modal volumes.In this article we present fabrication homogenous dense arrays axial InGaN/GaN nanotubes via...
By means of combining a very cost-effective lift-off process and nanosphere lithography technique, we have fabricated two dimensional (2D) photonic crystal (PhC) structures on an InGaN/GaN multiple quantum well structure. Significant enhancement in photoluminescence (PL) intensity has been observed when the emission wavelength is within bandgap. Time-resolved PL measurements shown that spontaneous rate strongly reduced by factor ∼4 due to PhC effect. As consequence, along 2D slab-plane...
An electrically injected hybrid organic/inorganic III-nitride white light-emitting diode (LED) has been fabricated by using a two-dimensional (2D) microhole array structure. The LED geometry significantly enhances proximity between the inorganic active-region and down-converting yellow organic polymers (OLEPs), enabling near-field nonradiative Förster resonance energy transfer (FRET) process with high efficiency while retaining excellent electrical characteristics of an unpatterned planar...
Abstract Carrier transport issues in a (11–22) semi-polar GaN based white light emitting diode (consisting of yellow and blue emissions) have been investigated by detailed simulations, demonstrating that the growth order InGaN quantum wells plays critically important role achieving emission. The needs to be first then well after n-type GaN. fundamental reason is due poor hole concentration distribution across whole region. In effectively capture holes both well, thin spacer has introduced...
By means of a cost-effective approach, we demonstrate GaN-based photoelectrode decorated with self-organized silver nano-islands employed for solar powered hydrogen generation, demonstrating 4 times increase in photocurrent compared reference sample without using any silver. Our exhibits 60% incident photon-to-electron conversion efficiency. The enhanced generation is attributed to significantly increased carrier rate as result strongly localized electric fields induced by surface plasmon...
Abstract Ligand exchange performed during or after the colloidal synthesis of nanocrystals (NCs) provides an efficient way to produce conductive NC solids for optoelectronics. Herein, a post‐synthetic ligand washing process is developed and applied two different combinations ligands perovskite NCs, namely robust green CsPbBr 3 NCs capped by didodecyldimethylammonium bromide near‐infrared FAPbI decorated weakly bound oleic acid ligands. The impact such processes on morphological...
By means of a cost effective nanosphere lithography technique, an InGaN/GaN multiple quantum well structure grown on (11–22) semipolar GaN has been fabricated into two dimensional nanorod arrays which form photonic crystal (PhC) structure. Such PhC demonstrates not only significantly increased emission intensity, but also enhanced polarization ratio the emission. This is due to inhibition in slab modes and then redistribution vertical direction, thus minimizing light scattering processes...
In this work, we demonstrate efficient light down-conversion via FRET in InGaN/GaN multiple quantum well (MQW) nanohole arrays, coated with green-emitting CsPbBr3 and FAPbBr3 nanocrystals (NCs) near-infrared (IR) FAPbI3 NC overlayers for solid-state lighting. Patterning the InGaN MQW into arrays allows a minimum nitride–NC separation while increasing heterointerfacial area, thus improving simultaneously nonradiative radiative transfer efficiencies. Detailed spectroscopic studies of...
Abstract Highly polarised white light emission from a hybrid organic/inorganic device has been achieved. The devices are fabricated by means of combining blue InGaN-based multiple quantum wells (MQWs) with one-dimensional (1D) grating structure and down-conversion F8BT yellow emitting polymer. 1D converts the unpolarised to highly polarised; achieved polymer filled aligned along periodic nano-channels as result enhanced nano-confinement. Optical polarization measurements show that our...
A “coherent” nanocavity structure has been designed on two-dimensional well-ordered InGaN/GaN nanodisk arrays with an emission wavelength in the green spectral region, leading to a massive enhancement resonance mode spectra region. By means of cost-effective nanosphere lithography technique, we have fabricated such multiple quantum well epiwafer and observed effect, which leads enhanced spontaneous (SE) rate. The SE rate confirmed by time resolved photoluminescence measurements. Due coherent...
Strong coupling of a confined optical field to the excitonic or vibronic transitions molecular material results in formation new hybrid states called polaritons. Such effects have been extensively studied Fabry-Pèrot microcavity structures where an organic is placed between two highly reflective mirrors. Recently, theoretical and experimental evidence has suggested that strong can be used modify chemical reactivity as well photophysical functionalities. However, geometry conventional limits...
The effect of surface states has been investigated in hybrid organic/inorganic white light emitting structures that employ high efficiency, nearfield non-radiative energy transfer (NRET) coupling. utilize blue InGaN/GaN multiple quantum well (MQW) nanorod arrays to minimize the separation with a yellow F8BT coating. Surface due exposed III-nitride surfaces nanostructures are found reduce NRET coupling rate. passivated by deposition silicon nitride layer on leading reduced recombination. A...
A prototype photoelectrode with a unique design has been fabricated using GaN microstripes grown on patterned Si substrate. The demonstrated record-high photocurrent density of 11 mA/cm2 upon one sun illumination and H2 generation rate up to 2.67 mL·cm–2·h–1. This performance step-change achieved due the contribution from both silicon substrate, as such combination covers wide spectral region (from ultraviolet bandgap infrared bandgap). Unlike conventional where thick AlN layer is required...