Matthew L Davies

Swansea University | SWAN · Sustainable Product Engineering Centre for Innovative Functional Industrial Coatings "SPECIFIC"

Time-resolved photoluminescence (TRPL) is a powerful tool to investigate charge carrier recombination processes in emissive materials. Perovskite materials are extremely promising for applications in solar cells; however, the interpretation of their TRPL is arduous due to the complicated nature of the recombination processes occurring in these mate...

Steroid hormones, being potent endocrine-disruptors, are a menace to human health and aquatic life. Herein, visible-light induced photocatalytic degradation of estrone (E1) by hexagonal copper selenide (CuSe) nanoflakes has been reported. CuSe was synthesised by a facile and low-temperature (100 oC) co-precipitation method and was characterised. Th...

Perovskite photovoltaics have shown great promise in device efficiency but also the promise of scalability through solution-processed manufacture. Efforts to scale perovskites have been taken through printable mesoporous scaffolds and slot die coating of flexible substrates roll to roll. However, to date there has been no demonstration of entirely...

Ruthenium(II) polypyridyl complexes (RPCs) that emit from metal-to-ligand charge transfer (MLCT) states have been developed as DNA probes and are being examined as potential anticancer agents. Here, we report that MLCT-emissive RPCs that bind DNA undergo Förster resonance energy transfer (FRET) with Cy5.5-labeled DNA, forming mega-Stokes shift FRET...

Among other factors, the electrochemical capacitor (EC) properties of graphene oxide (GO) are limited by conductivity issues emanating from high oxygen concentrations. Hence, innovative GO modifications, such as derivatisation and...

Lead halide perovskite solar cells (PSCs) are an emerging solar photovoltaic (PV) technology on the cusp of commercialisation, promising to deliver the lowest cost solar energy to date (>32 $/MWh)....

Silver sulfide (Ag2S) nanoparticles were incorporated into the electron transport layer (ETL) of thin-film organic photovoltaic cells to assist in light trapping and improve charge-transport processes. The solar cells were fabricated in an inverted device architecture design using a solar absorber composed of donor polymer poly[4,8-bis(5-(2-ethylhe...

Several strategies have been considered in search of more efficient organic materials for charge transfer in photovoltaic devices. Among them, the integration of donor-acceptor (D-A) functional units on a conjugated copolymer has been widely applied. In this framework, we evaluated four terpolymers made up of donor moieties derived from 9,9-dioctyl...

Abstract In practice, the capacitance from the electrochemical double layer formation on porous carbon‐based electrodes is still below preferred values, limiting their use in electrochemical capacitors. The current drive is to innovate ways that generate additional capacitance in the electrochemical double layer capacitive nature of carbon nanomate...

Molybdenum disulfide (MoS2) has received much interest due to its revolutionary development and advantageous properties; particularly in its configurable bandgap that can transit from indirect to direct as the phase changes from the bulk form into the monolayer. MoS2 has found use in a range of solar cell technology as a hole transport layer (HTL)...

Synergistic effects of the electronic structure and morphology in the PTB7-Th polymer and the nonfullerene acceptor ITIC molecule resulted in state-of-art systems for organic solar cells, achieving over 12% power conversion efficiency (PCE) values. Furthermore, the substitution of harmful halogenated solvents to environmentally friendly solvents th...

Energy and environmental challenges are global concerns that scientists are interested in alleviating. It is on this premise that we prepared boron/nitrogen graphene-coated Cu⁰/TiO2 (B/N-graphene-coated Cu/TiO2) photocatalyst of varying B:N ratios with dual functionality of H2 production and 2-Chlorophenol (2-CP) degradation. In-situ coating of Cu⁰...

Due to the finite nature, health and environmental hazards currently associated with the use of fossil energy resources, there is a global drive to hasten the development and deployment of renewable energy technologies. One such area encompasses perovskite solar cells (PSCs) that have shown photoconversion efficiencies (PCE) comparable to silicon-b...

High-performance electron transport layer (ETL) anode generally needs to form a uniform dense layer with suitable conduction band position and good electron transport properties. The TiO2 photoanode is primarily applied as the ETL because it is low-cost, has diverse thin-film preparation methods and has good chemical stability. However, pure TiO2 i...

For every three people on the planet, there are approximately two Tonnes (Te) of plastic waste. We show that carbon recovery from polystyrene (PS) plastic is enhanced by the coaddition of solvents to grow carbon nanotubes (CNTs) by liquid injection chemical vapour deposition. Polystyrene was loaded up to 4 wt% in toluene and heated to 780 °C in the...

For every three people on the planet there is approximately two Tonne (Te) of available plastic waste. We show that carbon recovery from polystyrene (PS) plastic is enhanced by the co-addition to solvents to grow carbon nanotubes (CNTs) by liquid injection chemical vapour deposition. Polystyrene was loaded up to 4 wt% in toluene and heated to 780 °...

Two terpolymers based on fluorene, benzothiadiazole, and carbazole monomer units were investigated as electron donor materials in organic solar cells. Variation of the microstructure, either statistical or in block, significantly affected the polymers' optoelectronic properties. Both terpolymers presented a high open-circuit voltage in photovoltaic...

Mesoscopic carbon‐based lead halide perovskite solar cells (CPSCs) represent a promising architecture for commercialisation in the field of perovskite photovoltaics as they are stable, potentially low cost and use easily scaled production methods. However, the use of toxic and psychoactive solvents such as dimethylformamide (DMF) and γ‐Butyrolacton...

Perovskite solar cells have emerged as a promising and highly efficient solar technology. Despite efficiencies continuing to climb, the prospect of industrial manufacture is in part hampered by concerns regarding the safety and sustainability of the solvents used in lab scale manufacture. In this paper, we aim to present a methodology for green sol...

Time-resolved photoluminescence (TRPL) spectroscopy is a powerful technique to investigate excited charge carrier recombinations in semiconductors and molecular systems. The analysis of the TRPL decays of many molecular systems (e.g. molecules and organic materials) is usually fairly straightfoward and can be fitted with an exponential function all...

Increasing recovery of critical raw materials (CRMs) from waste electrical and electronic equipment (WEEE) is a strategic priority to mitigate supply risks. Today, CRM recovery rates are generally low, with increases requiring new recovery processes and interface optimisation with pre-processing to ensure appropriate material flows for efficient re...

The setup and installation of a solar power system to demonstrate the performance of various battery chemistries unter two distinct storage sonditions is presented in this paper. Lead acid and lithium iron phosphate batteries were installed above ground and underground and their impact on system performance recorded.

The rapid rise in efficiencies of lead halide perovskite solar cells has hastened the case for commercialization. One of the key barriers, however, is stability of devices. In this issue of Joule, Zhou et al. studied the degradation mechanism of a FA-Cs mixed cation perovskite-based solar cell with experimental and modeling techniques to show that...

Colloidal metal chalcogenide quantum dots (QDs) have excellent quantum efficiency in light-matter interactions and good device stability. Although, QDs have been brought to the forefront as viable building blocks in bottom-up assembling semiconductor devices, the development of QD solar cell (QDSC) is still confronting considerable challenges compa...

Zero-valent copper (Cu0) is a promising co-catalyst in semiconductor-based photocatalysis as it is inexpensive and exhibits electronic properties similar to those of Ag and Au. However, its practical application in photocatalytic hydrogen production is limited by its susceptibility to oxidation forming less active Cu species. Herein, we have carrie...

Roll-to-roll coating of all active layers is demonstrated for a P-I-N perovskite solar cell stack, using a single step perovskite ink with an acetonitrile solvent system and flexible plastic substrate. A slot-die coating roll-to-roll process with a common coating speed for all layers is developed by using appropriate length meniscus guides as part...

Perovskite solar cells have attracted a great deal of attention thanks to their high efficiency, ease of manufacturing, and potential low cost. However, the stability of these devices is considered their main drawback and needs to be addressed. Mesoporous carbon perovskite solar cells (m‐CPSC), consisting of three mesoporous layers (TiO2/ZrO2/C) in...

Soil water repellency, that is, the reduced ability of soils to absorb water, is thought to be caused by organic coatings with predominantly non‐polar properties on soil particle surfaces. Given the important role of particle surface polarity in determining soil water repellency, we explored the use of fluorescent probes as a method for the direct...

Unsymmetrical porphyrins were rationally-designed and synthesized to investigate the relation between their structure, properties and adsorption geometries, and their relative performance as dyes in dye-sensitized solar cells. Photophysics, electrochemical and TiO2 anchoring properties of the new unsymmetrical N-glycolic acid amino phenyl porphyrin...

Organic-inorganic perovskite materials, such as methylammonium lead iodide, are good candidates for the next generation of solar cells with an impressive certified 23.7% power conversion efficiency. However, their development is impeded by their poor stability to oxygen, moisture, light and combinations of these. The bulk photoluminescence of perov...

Green technology for nanoparticles synthesis is considered to be of great significance in biomedical applications. Recently, low dimensional semiconductor cadmium sulfide (CdS) quantum dots (QDs) have raised great attention due to their optical properties and wide usage in biomedical studies. In our present work, we demonstrate a simple green synth...

Here, we briefly discuss the history of photovoltaic technology and highlight recent progression in its “next generation” of technology – solar cells that we can print in a variety of colours, shapes and sizes, and that can be integrated into the buildings around us. In this paper, we focus on the development of perovskite solar cells and discuss s...

On 5th September 2018, our Environment Sustainability and Energy Division (ESED) held an international scientific meeting at Burlington House, London looking at how the chemical sciences can develop solutions to the scientific and policy challenges to mitigate the issues of waste and resource efficiency for emerging technologies. This report provid...

Photovoltaics (PV) are increasingly important for electrification in rural Sub-Saharan Africa, but what is the best battery technology to use? To explore this question, a small-scale domestic PV system for South Africa (20-year lifetime) to deliver 1.42 kWh electricity from batteries overnight with 10-hour discharge was costed with various Li-ion,...

Colloidal TiO2 films have been prepared using a binder-free aqueous paste with Degussa P25 and hexafluorotitanic acid (H2TiF6), which was optimised for different substrates. Dye-sensitized solar cells (DSSC) fabricated using this paste were sintered at (ca. 393 K) and efficiencies (η) of 3.0, 4.2 and 6.1% were measured for devices using titanium fo...

We present a controlled, stepwise formation of methylammonium bismuth iodide (CH3NH3)3Bi2I9 perovskite films prepared via the vapour assisted solution process (VASP) by exposing BiI3 films to CH3NH3I (MAI) vapours for different reaction times, (CH3NH3)3Bi2I9 semiconductor films with tunable optoelectronic properties are obtained. Solar cells prepar...

Low dimensional semiconductor quantum dots (<10 nm) have received great attention for potential use in biomedical applications (diagnosis and therapy) for which larger nanoparticles (>10 nm) are not suitable. Here, we demonstrate a green, biogenic synthesis route for making CdS quantum dots (QDs) with 2-5 nm particle size using tea leaf extract (Ca...

In 2014 more than 1.2 billion people, which forms 16% of the world’s population, were without access to electricity. Over half of these were in sub-Saharan Africa (SSA). While photovoltaics (PV) appear to offer the possibility of ‘green’ electricity for rural areas, PV electricity generation and storage have major environmental impacts associated w...

We demonstrate improved performance and colour control of tri-bromide perovskite through co-sensitisation with organic dyes.

Precursors to three new 3,4-ethylenedioxythiophene (EDOT) incorportaing dyes have been synthesised via a one-pot C-H activation route using N,N-dimethylaniline as a donor group. We have extended this methodology to provide a convenient one-pot route to dye EDOT-Ph. The electrochemical and optical properties of the new dyes have been correlated with...

Photovoltaics, notably silicon PV, are becoming increasingly important in providing localised energy for rural communities in Africa. Although viewed as 'green', these technologies have environmental impacts associated with their production, use, and disposal, and full lifecycle optimisation for the circular economy is necessary to make every aspec...

The photochemistry and stability of fullerene films is found to be strongly dependent upon film nanomorphology. In particular, PC61BM blend films, dispersed with polystyrene, are found to be more susceptible to photobleaching in air than the more aggregated neat films. This enhanced photobleaching correlated with increased oxygen quenching of PC61B...

To celebrate the centenary of Science Progress we offer a short survey of the progress made over the past one hundred years in the research and application of photoinduced charge transfer. After a brief historical overview and introduction to photoinduced charge transfer, we discuss developments in the theory and practice of photography, photovolta...

Precursors to three new 3,4-ethylenedioxythiophene (EDOT) incorportaing dyes have been synthesised via a one-pot C-H activation route using N,N-dimethylaniline as a donor group. We have extended this methodology to provide a convenient one-pot route to dye EDOT-Ph. The electrochemical and optical properties of the new dyes have been correlated with...

Organic-inorganic solar cells based on lead halide perovskites are drawing unprecedented interest due to their high efficiency, potentially low fabrication cost, and favourable optical and electronic properties such as strong optical absorption in the visible and ultraviolet spectrum.1 A wide range of device architectures employing such perovskite...

We report a solvent-free approach to synthesizing organolead perovskites by using solid state reactions to coat perovskite crystals onto Al2O3 or TiO2 nanoparticles followed by addition of terpineol affording perovskite inks. We have bar cast these inks to produce photoactive perovskite thin films which are significantly more stable to humidity tha...

An extremely fast annealing technique for mixed-halide perovskite solar cells is presented. Using photonic flash sintering, we have demonstrated that a spin-coated perovskite precursor may be fully annealed in as little as 1 ms. Devices annealed in 1.15ms yielded power conversion efficiencies (PCEs) of upto 11.3% compared to 15.2% for samples annea...

Low-cost water-based P25-TiO 2 pastes were formulated and used to produce porous TiO 2 films in application to the fabrication of dye-sensitized solar cells. The structural properties of the films were characterized using a variety of techniques such as stylus profilometry, FEG-SEM imaging, BET surface area, and BJH pore size analyses. These were c...

The synthesis and full characterization of new half-squaraine dyes (Hf-SQ) containing two or three carboxylate-based linker units is reported and these dyes tested in dye-sensitized solar cell (DSC) devices. The data show improved device efficiency for a Hf-SQ dye with two linkers (η = 5.5%) compared to the highest efficiency Hf-SQ previously repor...

This paper presents a summary of our recent work on half-squaraine dyes for use as sensitizers in dye-sensitized solar cells. Our data include a review of the highest efficiency half-squaraine dyes to date. The discussion also considers how Jsc varies with functionalization of the Hf-SQ dyes and how these modifications affect device lifetime. The p...

A rapid annealing technique for CH3NH3PbI3 perovskite solar cells is presented. We report a co-deposited Al2O3- perovskite device annealed in under 2.5 seconds with a PCE of 10.0% compared to 10.9% for a 45 minute ovenannealed device.

This paper describes a facile method of self-assembling different metal oxide nanoparticles into nanostructured materials via di-carboxylate linkers (oxalic acid) using TiO2 as an example. In this method, the di-carboxylate linkers react with surface hydroxyls on metal oxide nanoparticles forming covalent, ester-like bonds, which enable the binding...

A key challenge that can unlock the potential of third generation photovoltaics (PV) is the development of low cost indium free flexible transparent electrodes to enable lightweight, transparent and metal mounted devices. A major breakthrough allows a highly conducting self-adhesive laminate electrode to be applied to devices at room temperature wh...

Developments in the field of organic-inorganic lead halide perovskite based solar cells have metaphorically opened the door to an exciting new solid state photovoltaic technology that retains the low cost and processability benefits of dye sensitised solar cells (DSCs). Encouraging device efficiencies of greater than 10% on both titania and alumina...

Uptake of photovoltaic (PV) devices is increasing rapidly despite difficult economic conditions. The majority of this uptake consist of rigid, rectangular, glass encapsulated cSi modules, which have been retro fitted to roofs. As the PV market grows, more varied products will be developed for a wider range of end uses (both indoor and outdoor). The...

Thermal analysis (TGA and DSC), coupled with evolved gas FTIR spectroscopy, have been used to study the changes occurring during, and differences between materials after, the annealing step of mixed-halide methylammonium lead halide perovskites. This is important because, to date, the material is the most efficient light harvester in highly efficie...

We describe the fastest dyeing of TiO2 photo-electrodes for dye-sensitized solar cells reported to date (< 2 min) at room temperature giving η = 7.5% for an N719/SQ1/CDCA mixture which is significantly higher than devices dyed for > 12 h using the same dye mixture (η = 5.5%). Time-lapse photography has been used to monitor the ultra-fast co-sensiti...

High efficiency, solution processed organic-inorganic trihalide perovskite solar cells are now a reality, meaning that perovskite photovoltaics have the potential to challenge more established photovoltaic technologies. To date, some of the most efficient solution processed perovskite solar cells feature a pre-deposited Al2O3 scaffold and we have s...

Nano-structured metal oxide films are key components of dye-sensitized (DSC) solar cells. Scaling such devices requires lower temperature processing to enable cheaper substrates to be used. In this context, we report a new and scalable method to sinter binder-containing metal oxide pastes to make DSC photo-electrodes at lower temperatures. Metal pe...