A5035456481- Optical Wireless Communication Technologies
- Semiconductor Lasers and Optical Devices
- Organic Light-Emitting Diodes Research
- Organic Electronics and Photovoltaics
- Advanced Photonic Communication Systems
- Optical Network Technologies
- Photonic and Optical Devices
- Luminescence and Fluorescent Materials
- Thin-Film Transistor Technologies
- X-ray Spectroscopy and Fluorescence Analysis
- solar cell performance optimization
- X-ray Diffraction in Crystallography
- Photoreceptor and optogenetics research
- Crystallization and Solubility Studies
- Advanced Chemical Physics Studies
- CO2 Reduction Techniques and Catalysts
- Spectroscopy and Quantum Chemical Studies
- Molecular Communication and Nanonetworks
- Conducting polymers and applications
- Electron and X-Ray Spectroscopy Techniques
- Laser-Matter Interactions and Applications
- Photochromic and Fluorescence Chemistry
- Impact of Light on Environment and Health
- Advanced Optical Network Technologies
- Semiconductor materials and interfaces
University of St Andrews
2006-2019
Scottish Universities Physics Alliance
2017
Institute of Organic Chemistry
2016
University of Strathclyde
2016
Coventry University
2016
University of Oxford
2016
Lund University
2011-2015
École Polytechnique Fédérale de Lausanne
2009-2011
Paul Scherrer Institute
2008
A 9 ps (3)MLCT lifetime was achieved by a Fe(II) complex based on C(NHC)^N(py)^C(NHC) pincer ligands. This is the longest known so far for any kind of complexes this abundant metal, and increased almost two orders magnitude compared to reference bis-terpyridine complex.
Abstract Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission diffuse scattering at SACLA facility track non-equilibrated electronic structural dynamics within a bimetallic donor–acceptor complex that contains...
This letter presents a novel technique to achieve high-speed visible light communication (VLC) using white generated by blue GaN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> LED and yellow fluorescent copolymer. We suitable for room illumination optimizing the ratio between electroluminescence of photoluminescence copolymer color converter. Taking advantage components'...
We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use a high-power picosecond laser operating an integer fraction rate storage ring allows exploitation up to two orders magnitude more x-ray photons than in previous schemes based on kHz lasers. Consequently, we demonstrate order increase signal-to-noise XAS molecular systems solution. This makes it possible investigate highly dilute...
Visible light communications (VLC) is an important emerging field aiming to use optical supplement Wi-Fi.This will greatly increase the available bandwidth so that demands for ever-higher data rates can be met.In this vision, solid-state lighting provide illumination while being modulated transmit data.An obstacle realizing vision are receivers, which need inexpensive, sensitive, fast, and have a large of view (FoV).One approach increasing sensitivity VLC receiver area receiver's...
The few-picosecond (ps) decay of terahertz (THz) photoconductivity typically observed for conjugated polymer:fullerene blends (at excitation fluencies ~10(15) photons/cm(2) per pulse) is shown to be a result charge pair annihilation two polymer:PCBM blends. At factor 100 lower density, the THz in hundreds ps time scale, implying that very high carrier mobility (~0.1 cm(2) V(-1) s(-1)) prevails long after formation, importance free formation organic solar cells.
Visible Light Communications (VLC) is a promising new technology which could offer higher data transmission rates than existing broadband RF/microwave wireless technologies. In this paper, we show that blend of semiconducting polymers can be used to make broadband, balanced color converter with very high modulation bandwidth replace commercial phosphors in hybrid LEDs for visible light communications. The resulting exploits partial Förster energy transfer the highly fluorescent green emitter...
A dilute fluorene copolymer produces enhanced optical amplification. High gain with 1000 times amplification and a long lifetime is achieve in only 1mm of the material, exciton–exciton annihilation suppressed.
Ultrafast X-ray absorption spectroscopy is a powerful tool to observe electronic and geometric structures of short-lived reaction intermediates. The ab initioFEFF9 code applied simulate the Pt L3-edge XANES spectrum photocatalytic diplatinum molecule [Pt2(P2O5H2)4]4− photo-induced changes that occur therein. spectra are interpreted within XAFS-like scattering theoretical framework (bound-continuum transitions) or in terms final-state local l-projected density states (LDOS) (bound–bound...
Star-shaped organic semiconductors with boron dipyrromethene (BODIPY) cores are color-conversion materials for blue LED-based visible light communications. The difference between 0 and 1 bits is resolved in colour-converted data links at 100 Mb s−1. BODIPY modulation bandwidth eight times higher than that measured using conventional phosphor color converters. This an open access article under the terms of Creative Commons Attribution License, which permits use, distribution reproduction any...
Abstract This paper presents a novel fluorescent receiver for visible light communications that combines broad field of view (FoV) with significant gain, and simultaneously enables wavelength division multiplexing (WDM) data communications. These characteristics are achieved by creating includes stack two optical antennas, each designed to receive different part the spectrum create separable communication channels. The device outperforms theoretical étendue limit in terms combination FoV...
In this paper we studied carrier drift dynamics in APFO3:PC61BM solar cells of varied stoichiometry (2:1, 1:1, and 1:4 APFO3:PC61BM) over a wide time range, from subpicoseconds to microseconds with combination ultrafast optical electric field probing conventional transient integrated photocurrent techniques. Carrier extraction are strongly dependent: the speed electron or hole increases higher concentration PC61BM polymer, respectively. The sample 80% takes place during hundreds picoseconds,...
Organic semiconducting materials have been researched for novel optoelectronic devices due to their efficient light emission and high gain properties. Such range from organic light-emitting diodes solar cells lasers amplifiers. This paper explores the research carried out on one of these devices: semiconductor amplifiers that shown give gains 20-40 dB in solution solid state.
A compact, solid state optical amplifier based on the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] has been demonstrated. The was optically pumped. Gratings were used to couple signal into and out of film. transmitted amplified over 100 times in a 1mm long waveguide giving 21dB gain at 630nm. &gt;13dB observed 615 650nm bandwidth &gt;26THz. dynamics pump densities below 5μJ∕cm2 are described by an exciton-exciton annihilation model. At higher...
This letter reports a demonstration of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> multiple-input multiple-output (MIMO) indoor visible-light communication (VLC) system using novel fluorescent optical concentrator-based receiver. potentially allows high degree spatial multiplexing to be achieved simple receiver structure that can have wide field-of-view. Details...
The output of red (∼ 650 nm) light emitting polymer DFB lasers can be modulated by exposure to infrared 1.3 μm) control pulses that de-populate the S1 level (see figure). This offers prospect an effective wavelength conversion between silica and optical fibre communication wavelengths.
This paper presents a demonstration of polymer based colour-converters and GaN micro-LEDs for red-green-blue white-light visible-light-communication. By applying an optimised orthogonal-frequency-division-multiplexing scheme, aggregate-rate 2.3 Gb/s is demonstrated.
In this paper, we study a family of solid-state, organic semiconductors for visible light communications. The star-shaped molecules have boron-dipyrromethene (BODIPY) core with range side arm lengths which control the photophysical properties. emit red photoluminescence quantum yields ranging from 22% to 56%. Thin films most promising BODIPY were used as colour converter film enabled conversion modulation bandwidth 73 MHz, is 16 times higher than that typical phosphor in LED lighting...
Charge separation and extraction dynamics were investigated in high-performance bulk heterojunction solar cells made from the polymer PTB7 soluble fullerene PC71BM on a broad time scale subpicosecond to microseconds using ultrafast optical probing of carrier drift integral-mode photocurrent measurements. We show that short circuit current is determined by charge pairs into free carriers, which strongly influenced blend composition. This found be efficient fullerene-rich blends where high...
We report a study of blends semiconducting polymers as saturated red color converters to replace commercial phosphors in hybrid Light emitting diodes (LEDs) for visible light communication (VLC). By blending two star-shaped organic semiconductor molecules, we found near complete energy transfer (&gt;90% efficiency) from the green-emitting truxene-cored compound T4BT-B red-emitting boron dipyrromethene (BODIPY) cored materials. Furthermore, have demonstrated capability these materials...
We report the synthesis, photophysics and application of a novel semiconducting polymer as colour converter for high speed visible light communication.
Color converting films of colloidal quantum dots (CQDs) encapsulated with flexible glass are integrated microsize GaN LEDs (μLEDs) in order to form optical sources for high-speed visible light communications (VLC). VLC is an emerging technology that uses white and/or colored from combine illumination and display functions the transmission data. The glass/CQD format addresses issue limited modulation speed typical phosphor-converted while enhancing photostability color converters facilitating...
Given the imminent radio frequency spectrum crunch, Visible Light Communication (VLC) is being proposed as an alternative wireless technology allowing for scalable connectivity to potentially millions of mobile and Internet-of- Things (IoT) devices. A VLC system uses a photo-detector (PD) receiver that converts optically modulated light from source into electrical signal. The corresponding bandwidth typically inversely proportional PD active area. Consequently, construct high-speed link,...
Broadband transient absorption spectroscopy is combined with ultrafast carrier drift measurements to study dissociation of photogenerated charge pairs in efficient photovoltaic blends the electron donating polymer PTB7 acceptor PC71BM. A high ensemble-average mobility sum electrons and holes observed which independent applied electric field above 12 V/μm indicates nearly barrierless pair at room temperature on a picosecond time scale. High efficiency this material achieved by combination...
The photochemical reactions performed by transition metal complexes have been proposed as viable routes towards solar energy conversion and storage into other forms that can be conveniently used in our everyday applications. In order to develop efficient materials, it is necessary identify, characterize optimize the elementary steps of entire process on atomic scale. To this end, we studied photoinduced electronic structural dynamics two heterobimetallic ruthenium–cobalt dyads, which belong...