Imperial College London

Dr Matyas Daboczi

Faculty of EngineeringDepartment of Chemical Engineering

Research Associate
 
 
 
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Contact

 

m.daboczi Website

 
 
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Location

 

614Roderic Hill BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

31 results found

Zhu Z, Daboczi M, Chen M, Xuan Y, Liu X, Eslava Set al., 2024, Ultrastable halide perovskite CsPbBr3 photoanodes achieved with electrocatalytic glassy-carbon and boron-doped diamond sheets., Nat Commun, Vol: 15, Pages: 2791-2791

Halide perovskites exhibit exceptional optoelectronic properties for photoelectrochemical production of solar fuels and chemicals but their instability in aqueous electrolytes hampers their application. Here we present ultrastable perovskite CsPbBr3-based photoanodes achieved with both multifunctional glassy carbon and boron-doped diamond sheets coated with Ni nanopyramids and NiFeOOH. These perovskite photoanodes achieve record operational stability in aqueous electrolytes, preserving 95% of their initial photocurrent density for 168 h of continuous operation with the glassy carbon sheets and 97% for 210 h with the boron-doped diamond sheets, due to the excellent mechanical and chemical stability of glassy carbon, boron-doped diamond, and nickel metal. Moreover, these photoanodes reach a low water-oxidation onset potential close to +0.4 VRHE and photocurrent densities close to 8 mA cm-2 at 1.23 VRHE, owing to the high conductivity of glassy carbon and boron-doped diamond and the catalytic activity of NiFeOOH. The applied catalytic, protective sheets employ only earth-abundant elements and straightforward fabrication methods, engineering a solution for the success of halide perovskites in stable photoelectrochemical cells.

Journal article

Fernández-Catalá J, Jussila L, Daboczi M, Temerov F, Eslava S, Greco R, Cao Wet al., 2023, Shape-Controlled Synthesis of Cu3TeO6 Nanoparticles with Photocatalytic Features., Cryst Growth Des, Vol: 23, Pages: 8828-8837, ISSN: 1528-7483

Cu3TeO6 (CTO) has been synthesized by hydrothermal synthesis applying different pH values without any template or a calcination step to control the crystalline phase and the morphology of nanoparticles. The physicochemical properties characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy, and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy techniques revealed that the pH values significantly influence the crystal growth. In acidic media (pH = 2), crystal growth has not been achieved. At pH = 4, the yield is low (10%), and the CTO presents irregular morphology. At pH = 6, the yield increases (up to 71%) obtaining an agglomeration of nanoparticles into spherical morphology. At basic conditions (pH = 8), the yield increases up to 90% and the morphology is the same as the sample obtained at pH = 6. At high basic conditions (pH = 10), the yield is similar (92%), although the morphology changes totally to dispersed nanoparticles. Importantly, the as-prepared CTO semiconductor presents photocatalytic activity for H2 production using triethanolamine as a sacrificial agent under visible light illumination. The results also revealed that the nanoparticles agglomerated in a spherical morphology with larger surface area presented almost double activities in H2 production compared to heterogeneously sized particles. These results highlight the suitable optoelectronic properties, including optical band gap, energy levels, and photoconductivity of CTO semiconductors for their use in photocatalytic H2 production.

Journal article

Liu SC, Lin HY, Hsu SE, Wu DT, Sathasivam S, Daboczi M, Hsieh HJ, Zeng CS, Hsu TG, Eslava S, Macdonald TJ, Lin CTet al., 2023, Highly reproducible self-assembled monolayer based perovskite solar cells via amphiphilic polyelectrolyte, Journal of Materials Chemistry A, Vol: 12, Pages: 2856-2866, ISSN: 2050-7488

Self-assembled monolayers (SAM) have attracted a lot of attention in perovskite solar cells (PSCs) due to their high efficiency in both single junction and tandem devices. However, inferior reproducibility originating from poor surface coverage and voids in the perovskite layer at the buried interface still limits their widespread use. Herein, we report a facile method to significantly improve the reproducibility of PSCs by employing an amphiphilic conjugated polyelectrolyte between SAMs and perovskite layers. Application of the polyelectrolyte leads to a 200 meV shallower perovskite Fermi level, allowing a desirable, significantly increased band bending at the SAM/perovskite interface. Moreover, imaging the buried perovskite interface by a novel technique reveals that interfacial voids are minimised by the polyelectrolyte leading to complete coverage of the ITO/SAM surface. As a result, remarkable fill factors over 0.84 and power conversion efficiencies exceeding 22.5% are achieved. The PSCs demonstrate exceptional reproducibility and high performance, as evidenced by an average fill factor of 0.81 with a remarkably low standard deviation of less than 0.01 across 50 individual devices. These results demonstrate a universal method to improve the reproducibility of PSCs containing commonly used SAMs and open the door for wider use of amphiphilic conjugated polyelectrolytes in optoelectronic devices.

Journal article

Daboczi M, Cui J, Temerov F, Eslava Set al., 2023, Scalable All-Inorganic Halide Perovskite Photoanodes with >100 h Operational Stability Containing Earth-Abundant Materials., Adv Mater, Vol: 35

The application of halide perovskites in the photoelectrochemical generation of solar fuels and feedstocks is hindered by the instability of perovskites in aqueous electrolytes and the use of expensive electrode and catalyst materials, particularly in photoanodes driving kinetically slow water oxidation. Here, solely earth-abundant materials are incorporated to fabricate a CsPbBr3 -based photoanode that reaches a low onset potential of +0.4 VRHE and 8 mA cm-2 photocurrent density at +1.23 VRHE for water oxidation, close to the radiative efficiency limit of CsPbBr3 . This photoanode retains 100% of its stabilized photocurrent density for more than 100 h of operation by replacing once the inexpensive graphite sheet upon signs of deterioration. The improved performance is due to an efficiently electrodeposited NiFeOOH catalyst on a protective self-adhesive graphite sheet, and enhanced charge transfer achieved by phase engineering of CsPbBr3 . Devices with >1 cm2 area, and low-temperature processing demonstrate the potential for low capital cost, stable, and scalable perovskite photoanodes.

Journal article

Baghdadi Y, Temerov F, Cui J, Daboczi M, Rattner E, Sena MS, Itskou I, Eslava Set al., 2023, Cs3Bi2Br9/g-C3N4 Direct Z-Scheme Heterojunction for Enhanced Photocatalytic Reduction of CO2 to CO., Chem Mater, Vol: 35, Pages: 8607-8620, ISSN: 0897-4756

Lead-free halide perovskite derivative Cs3Bi2Br9 has recently been found to possess optoelectronic properties suitable for photocatalytic CO2 reduction reactions to CO. However, further work needs to be performed to boost charge separation for improving the overall efficiency of the photocatalyst. This report demonstrates the synthesis of a hybrid inorganic/organic heterojunction between Cs3Bi2Br9 and g-C3N4 at different ratios, achieved by growing Cs3Bi2Br9 crystals on the surface of g-C3N4 using a straightforward antisolvent crystallization method. The synthesized powders showed enhanced gas-phase photocatalytic CO2 reduction in the absence of hole scavengers of 14.22 (±1.24) μmol CO g-1 h-1 with 40 wt % Cs3Bi2Br9 compared with 1.89 (±0.72) and 5.58 (±0.14) μmol CO g-1 h-1 for pure g-C3N4 and Cs3Bi2Br9, respectively. Photoelectrochemical measurements also showed enhanced photocurrent in the 40 wt % Cs3Bi2Br9 composite, demonstrating enhanced charge separation. In addition, stability tests demonstrated structural stability upon the formation of a heterojunction, even after 15 h of illumination. Band structure alignment and selective metal deposition studies indicated the formation of a direct Z-scheme heterojunction between the two semiconductors, which boosted charge separation. These findings support the potential of hybrid organic/inorganic g-C3N4/Cs3Bi2Br9 Z-scheme photocatalyst for enhanced CO2 photocatalytic activity and improved stability.

Journal article

Wang Y, Daboczi M, Zhang M, Briscoe J, Kim J-S, Yan H, Dunn Set al., 2023, Origin of the switchable photocurrent direction in BiFeO<sub>3</sub> thin films, MATERIALS HORIZONS, ISSN: 2051-6347

Journal article

Cui J, Daboczi M, Cui Z, Gong M, Flitcroft J, Skelton J, Parker SC, Eslava Set al., 2023, BiVO<sub>4</sub> Photoanodes Enhanced with Metal Phosphide Co-Catalysts: Relevant Properties to Boost Photoanode Performance, SMALL, ISSN: 1613-6810

Journal article

Yang M, Cui J, Daboczi M, Law RV, Luke J, Kim J-S, Hankin A, Eslava Set al., 2023, Interplay between Collective and Localized Effects of Point Defects on Photoelectrochemical Performance of TiO<sub>2</sub> Photoanodes for Oxygen Evolution, ADVANCED MATERIALS INTERFACES, ISSN: 2196-7350

Journal article

Stewart K, Pagano K, Tan E, Daboczi M, Rimmele M, Luke J, Eslava S, Kim J-Set al., 2023, Understanding Effects of Alkyl Side-Chain Density on Polaron Formation Via Electrochemical Doping in Thiophene Polymers, ADVANCED MATERIALS, ISSN: 0935-9648

Journal article

Greco R, Baxauli-Marin L, Temerov F, Daboczi M, Eslava S, Niu Y, Zakharov A, Zhang M, Li T, Cao Wet al., 2023, Activation of 2D cobalt hydroxide with 0D cobalt oxide decoration for microplastics degradation and hydrogen evolution, CHEMICAL ENGINEERING JOURNAL, Vol: 471, ISSN: 1385-8947

Journal article

Daboczi M, 2023, Virtually free clean hydrogen generation by photoelectrochemical devices?, Matter, Vol: 6, Pages: 2594-2596, ISSN: 2590-2393

This preview highlights a halide perovskite-based photoelectrochemical device that allows simultaneous generation of clean hydrogen and production of value-added product from polymeric waste materials with high selectivity. This concept provides an exciting new avenue for significant cost reduction of solar hydrogen.

Journal article

Yan H, Cong S, Daboczi M, Limbu S, Hamilton I, Kwon S, Rapley CL, Tahir SM, Kerherve G, Payne D, Heeney M, Kim J-Set al., 2023, Ionic Density Control of Conjugated Polyelectrolytes via Postpolymerization Modification to Enhance Hole-Blocking Property for Highly Efficient PLEDs with Fast Response Times, ADVANCED OPTICAL MATERIALS, ISSN: 2195-1071

Journal article

He Q, Basu A, Cha H, Daboczi M, Panidi J, Tan L, Hu X, Huang CC, Ding B, White AJP, Kim J-S, Durrant JR, Anthopoulos TD, Heeney Met al., 2023, Ultra-Narrowband Near-Infrared Responsive J-Aggregates of Fused Quinoidal Tetracyanoindacenodithiophene, ADVANCED MATERIALS, Vol: 35, ISSN: 0935-9648

Journal article

Sena MS, Cui J, Baghdadi Y, Rattner E, Daboczi M, Lopes-Moriyama AL, dos Santos AG, Eslava Set al., 2023, Lead-Free Halide Perovskite Cs2AgBiBr6/Bismuthene Composites for Improved CH4 Production in Photocatalytic CO2 Reduction, ACS APPLIED ENERGY MATERIALS, ISSN: 2574-0962

Journal article

Cui J, Daboczi M, Regue M, Chin Y, Pagano K, Zhang J, Isaacs MA, Kerherve G, Mornto A, West J, Gimenez S, Kim J, Eslava Set al., 2022, 2D bismuthene as a functional interlayer between BiVO4 and NiFeOOH for enhanced oxygen-evolution photoanodes, Advanced Functional Materials, Vol: 32, Pages: 1-12, ISSN: 1616-301X

BiVO4 has attracted wide attention for oxygen-evolution photoanodes in water-splitting photoelectrochemical devices. However, its performance is hampered by electron-hole recombination at surface states. Herein, partially oxidized two-dimensional (2D) bismuthene is developed as an effective, stable, functional interlayer between BiVO4 and the archetypal NiFeOOH co-catalyst. Comprehensive (photo)electrochemical and surface photovoltage characterizations show that NiFeOOH can effectively increase the lifetime of photogenerated holes by passivating hole trap states of BiVO4; however, it is limited in influencing electron trap states related to oxygen vacancies (VO). Loading bismuthene on BiVO4 photoanodes increases the density of VO that are beneficial for the oxygen evolution reaction via the formation of oxy/hydroxyl-based water oxidation intermediates at the surface. Moreover, bismuthene increases interfacial band bending and fills the VO-related electron traps, leading to more efficient charge extraction. With the synergistic interaction of bismuthene and NiFeOOH on BiVO4, this composite photoanode achieves a 5.8-fold increase in photocurrent compared to bare BiVO4 reaching a stable 3.4 (±0.2) mA cm–2 at a low bias of +0.8 VRHE or 4.7(±0.2) mA cm–2 at +1.23 VRHE. The use of 2D bismuthene as functional interlayer provides a new strategy to enhance the performance of photoanodes.

Journal article

Chin Y-C, Daboczi M, Henderson C, Luke J, Kim J-Set al., 2022, Suppressing PEDOT:PSS doping-induced interfacial recombination loss in perovskite solar cells, ACS Energy Letters, Vol: 7, Pages: 560-568, ISSN: 2380-8195

PEDOT:PSS is widely used as a hole transport layer (HTL) in perovskite solar cells (PSCs) due to its facile processability, industrial scalability, and commercialization potential. However, PSCs utilizing PEDOT:PSS suffer from strong recombination losses compared to other organic HTLs. This results in lower open-circuit voltage (VOC) and power conversion efficiency (PCE). Most studies focus on doping PEDOT:PSS to improve charge extraction, but it has been suggested that a high doping level can cause strong recombination losses. Herein, we systematically dedope PEDOT:PSS with aqueous NaOH, raising its Fermi level by up to 500 meV, and optimize its layer thickness in p-i-n devices. A significant reduction of recombination losses at the dedoped PEDOT:PSS/perovskite interface is evidenced by a longer photoluminescence lifetime and higher magnitude of surface photovoltage, leading to an increased device VOC, fill factor, and PCE. These results provide insights into the relationship between doping level of HTLs and interfacial charge carrier recombination losses.

Journal article

Daboczi M, Ratnasingham SR, Mohan L, Pu C, Hamilton I, Chin Y-C, McLachlan MA, Kim J-Set al., 2021, Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells, ACS ENERGY LETTERS, Vol: 6, Pages: 3970-3981, ISSN: 2380-8195

Journal article

Mohan L, Ratnasingham SR, Panidi J, Daboczi M, Kim J-S, Anthopoulos TD, Briscoe J, McLachlan MA, Kreouzis Tet al., 2021, Determining out-of-plane hole mobility in CuSCN via the time-of-flight technique to elucidate its function in perovskite solar cells, ACS Applied Materials and Interfaces, Vol: 13, Pages: 38499-38507, ISSN: 1944-8244

Copper(I) thiocyanate (CuSCN) is a stable, low-cost, solution-processable p-type inorganic semiconductor used in numerous optoelectronic applications. Here, for the first time, we employ the time-of-flight (ToF) technique to measure the out-of-plane hole mobility of CuSCN films, enabled by the deposition of 4 μm-thick films using aerosol-assisted chemical vapor deposition (AACVD). A hole mobility of ∼10–3 cm2/V s was measured with a weak electric field dependence of 0.005 cm/V1/2. Additionally, by measuring several 1.5 μm CuSCN films, we show that the mobility is independent of thickness. To further validate the suitability of our AACVD-prepared 1.5 μm-thick CuSCN film in device applications, we demonstrate its incorporation as a hole transport layer (HTL) in methylammonium lead iodide (MAPbI3) perovskite solar cells (PSCs). Our AACVD films result in devices with measured power conversion efficiencies of 10.4%, which compares favorably with devices prepared using spin-coated CuSCN HTLs (12.6%), despite the AACVD HTLs being an order of magnitude thicker than their spin-coated analogues. Improved reproducibility and decreased hysteresis were observed, owing to a combination of excellent film quality, high charge-carrier mobility, and favorable interface energetics. In addition to providing a fundamental insight into charge-carrier mobility in CuSCN, our work highlights the AACVD methodology as a scalable, versatile tool suitable for film deposition for use in optoelectronic devices.

Journal article

Vasilopoulou M, Mohd Yusoff ARB, Daboczi M, Conforto J, Gavim AEX, da Silva WJ, Macedo AG, Soultati A, Pistolis G, Schneider FK, Dong Y, Jacoutot P, Rotas G, Jang J, Vougioukalakis GC, Chochos CL, Kim J-S, Gasparini Net al., 2021, High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence, Nature Communications, Vol: 12, ISSN: 2041-1723

Blue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m-2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures.

Journal article

Kyeong M, Lee J, Daboczi M, Stewart K, Yao H, Cha H, Luke J, Lee K, Durrant JR, Kim J-S, Hong Set al., 2021, Organic cathode interfacial materials for non-fullerene organic solar cells, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 9, Pages: 13506-13514, ISSN: 2050-7488

Journal article

Luke J, Correa L, Rodrigues J, Martins J, Daboczi M, Bagnis D, Kim J-Set al., 2021, A Commercial Benchmark: Light-Soaking Free, Fully Scalable, Large-Area Organic Solar Cells for Low-Light Applications, ADVANCED ENERGY MATERIALS, Vol: 11, ISSN: 1614-6832

Journal article

Ratnasingham SR, Mohan L, Daboczi M, Degousée T, Binions R, Fenwick O, Kim J-S, McLachlan MA, Briscoe Jet al., 2021, Novel scalable aerosol-assisted CVD route for perovskite solar cells, Materials Advances, Vol: 2, Pages: 1606-1612

Organo-metal halide perovskite research has progressed rapidly, with photovoltaic (PV) devices achieving over 25% power conversion efficiency (PCE). However, scalable production of these devices is an ongoing challenge. We demonstrate the growth of methylammonium lead triiodide (MAPI) films via a novel two-step aerosol-assisted chemical vapour deposition (AACVD) method leading to the first ever perovskite-based PV devices using active layers deposited by AACVD. This is a scalable deposition process, requiring less complex equipment than conventional CVD. Furthermore, our method utilises methanol (MeOH) as the only solvent, as opposed to harmful solvents typically used in perovskite processing. Structural and optical characterization confirms successful formation of MAPI with no secondary phases and an optical bandgap of ∼1.58 eV. The final film had large grains (order of μm), with thickness ranging from 500–1100 nm. These films were used to fabricate working PV devices resulting in a champion PCE of 5.4%. While films demonstrated high structural and compositonal quality, we identified large film roughness as a limiting factor in device PCE, and elucidate the origin of this via detailed study of the film growth, which reveals a unique multi-step film formation process.

Journal article

Daboczi M, Kim J, Lee J, Kang H, Hamilton I, Lin C-T, Dimitrov SD, McLachlan MA, Lee K, Durrant JR, Kim J-Set al., 2020, Towards efficient integrated perovskite/organic bulk heterojunction solar cells: interfacial energetic requirement to reduce charge carrier recombination losses, Advanced Functional Materials, Vol: 30, Pages: 1-8, ISSN: 1616-301X

Integrated perovskite/organic bulk heterojunction (BHJ) solar cells have the potential to enhance the efficiency of perovskite solar cells by a simple one‐step deposition of an organic BHJ blend photoactive layer on top of the perovskite absorber. It is found that inverted structure integrated solar cells show significantly increased short‐circuit current (J sc) gained from the complementary absorption of the organic BHJ layer compared to the reference perovskite‐only devices. However, this increase in J sc is not directly reflected as an increase in power conversion efficiency of the devices due to a loss of fill factor. Herein, the origin of this efficiency loss is investigated. It is found that a significant energetic barrier (≈250 meV) exists at the perovskite/organic BHJ interface. This interfacial barrier prevents efficient transport of photogenerated charge carriers (holes) from the BHJ layer to the perovskite layer, leading to charge accumulation at the perovskite/BHJ interface. Such accumulation is found to cause undesirable recombination of charge carriers, lowering surface photovoltage of the photoactive layers and device efficiency via fill factor loss. The results highlight a critical role of the interfacial energetics in such integrated cells and provide useful guidelines for photoactive materials (both perovskite and organic semiconductors) required for high‐performance devices.

Journal article

Luo H, Dimitrov S, Daboczi M, Kim J-S, Guo Q, Fang Y, Stoeckel M-A, Samori P, Fenwick O, Sobrido ABJ, Wang X, Titirici M-Met al., 2020, Nitrogen-Doped Carbon Dots/TiO<sub>2</sub> Nanoparticle Composites for Photoelectrochemical Water Oxidation, ACS APPLIED NANO MATERIALS, Vol: 3, Pages: 3371-3381, ISSN: 2574-0970

Journal article

Lin C-T, Lee J, Kim J, Macdonald TJ, Ngiam J, Xu B, Daboczi M, Xu W, Pont S, Park B, Kang H, Kim J-S, Payne DJ, Lee K, Durrant JR, McLachlan MAet al., 2020, Origin of open-circuit voltage enhancements in planar Perovskite solar cells induced by addition of bulky organic cations, Advanced Functional Materials, Vol: 30, ISSN: 1616-301X

The origin of performance enhancements in p‐i‐n perovskite solar cells (PSCs) when incorporating low concentrations of the bulky cation 1‐naphthylmethylamine (NMA) are discussed. A 0.25 vol % addition of NMA increases the open circuit voltage (Voc) of methylammonium lead iodide (MAPbI3) PSCs from 1.06 to 1.16 V and their power conversion efficiency (PCE) from 18.7% to 20.1%. X‐ray photoelectron spectroscopy and low energy ion scattering data show NMA is located at grain surfaces, not the bulk. Scanning electron microscopy shows combining NMA addition with solvent assisted annealing creates large grains that span the active layer. Steady state and transient photoluminescence data show NMA suppresses non‐radiative recombination resulting from charge trapping, consistent with passivation of grain surfaces. Increasing the NMA concentration reduces device short‐circuit current density and PCE, also suppressing photoluminescence quenching at charge transport layers. Both Voc and PCE enhancements are observed when bulky cations (phenyl(ethyl/methyl)ammonium) are incorporated, but not smaller cations (Cs/MA)—indicating size is a key parameter. Finally, it demonstrates that NMA also enhances mixed iodide/bromide wide bandgap PSCs (Voc of 1.22 V with a 1.68 eV bandgap). The results demonstrate a facile approach to maximizing Voc and provide insights into morphological control and charge carrier dynamics induced by bulky cations in PSCs.

Journal article

Daboczi M, Hamilton I, Xu S, Luke J, Limbu S, Lee J, McLachlan MA, Lee K, Durrant JR, Baikie ID, Kim J-Set al., 2019, Origin of Open-Circuit Voltage Losses in Perovskite Solar Cells Investigated by Surface Photovoltage Measurement, ACS Applied Materials &amp; Interfaces, Vol: 11, Pages: 46808-46817, ISSN: 1944-8244

Journal article

Du T, Xu W, Daboczi M, Kim J, Xu S, Lin C-T, Kang H, Lee K, Heeney MJ, Kim J-S, Durrant JR, McLachlan MAet al., 2019, p-Doping of organic hole transport layers in p–i–n perovskite solar cells: correlating open-circuit voltage and photoluminescence quenching, Journal of Materials Chemistry A, Vol: 7, Pages: 18971-18979, ISSN: 2050-7488

Doping is a widely implemented strategy for enhancing the inherent electronic properties of charge transport layers in photovoltaic (PV) devices. Here, in direct contrast to existing understanding, we find that a reduction in p-doping of the organic hole transport layer (HTL) leads to substantial improvements in PV performance in planar p–i–n perovskite solar cells (PSCs), driven by improvements in open circuit voltage (VOC). Employing a range of transient and steady state characterisation tools, we find that the improvements of VOC correlate with reduced surface recombination losses in less p-doped HTLs. A simple device model including screening of bulk electric fields in the perovskite layer is used to explain this observation. In particular, photoluminescence (PL) emission of complete solar cells shows that efficient performance is correlated to a high PL intensity at open circuit and a low PL intensity at short circuit. We conclude that desirable transport layers for p–i–n PSCs should be charge selective contacts with low doping densities.

Journal article

He Q, Shahid M, Panidi J, Marsh AV, Huang W, Daboczi M, Kim J-S, Fei Z, Anthopoulos TD, Heeney Met al., 2019, A versatile star-shaped organic semiconductor based on benzodithiophene and diketopyrrolopyrrole, Journal of Materials Chemistry C, Vol: 7, Pages: 6622-6629, ISSN: 2050-7526

We report the synthesis of a new star-shaped π-conjugated oligomer, BDT(DPP)4, containing a benzodithiophene core and four diketopyrrolopyrrole arms. The thermal, electrochemical and optical properties are characterized and the results complemented by computational studies. The utility of the molecule is demonstrated in both solar cell and field-effect transistor devices. In the former, BDT(DPP)4 displays low efficiency when used as an acceptor in blends with poly(3-hexylthiophene) but exhibits promising performance as a donor, in blends with either a fullerene or a non-fullerene acceptor. In field-effect transistors BDT(DPP)4 exhibits typical p-type transistor behavior, which is in accordance with its better donor performance in solar cell devices.

Journal article

Wang Y, Daboczi M, Mesa CA, Ratnasingham SR, Kim JS, Durrant JR, Dunn S, Yan H, Briscoe Jet al., 2019, Bi₂Fe₄O₉ thin films as novel visible-light-active photoanodes for solar water splitting, Journal of Materials Chemistry A, Vol: 7, Pages: 9537-9541, ISSN: 2050-7496

We report the chemical solution deposition (CSD) of a phase-pure Bi2Fe4O9 thin film for use as a photoanode in photoelectrochemical (PEC) water splitting. The energy levels of Bi2Fe4O9 films have been measured and n-type characteristics have been confirmed. With band gaps determined as 2.05 eV (indirect) and 2.80 eV (direct) and valence and conduction bands straddling the water oxidation and reduction potentials, this material is highly promising as a photocatalyst for solar water splitting. The photocurrent of a planar photoanode reached 0.1 mA cm−2 at 1.23 VNHE under AM1.5G illumination. The addition of H2O2 as a hole scavenger increased the photocurrent to 0.25 mA cm−2, indicating hole injection is one limiting factor to the performance. The performance was enhanced by nearly 5-fold when the Bi2Fe4O9 photoanode is coupled to a Co–Pi surface co-catalyst. The photoanode also shows excellent stability with no change in photocurrent over three hours of continuous illumination. These results indicate that this material represents a promising addition to the growing selection of low-cost, stable photocatalysts for use in solar water splitting.

Journal article

Lee S, Kim DB, Hamilton I, Daboczi M, Nam YS, Lee BR, Zhao B, Jang CH, Friend RH, Kim J-S, Song MHet al., 2018, Control of interface defects for efficient and stable quasi-2D Perovskite light-emitting diodes using nickel oxide hole injection layer, Advanced Science, Vol: 5, ISSN: 2198-3844

Metal halide perovskites (MHPs) have emerged as promising materials for light‐emitting diodes owing to their narrow emission spectrum and wide range of color tunability. However, the low exciton binding energy in MHPs leads to a competition between the trap‐mediated nonradiative recombination and the bimolecular radiative recombination. Here, efficient and stable green emissive perovskite light‐emitting diodes (PeLEDs) with an external quantum efficiency of 14.6% are demonstrated through compositional, dimensional, and interfacial modulations of MHPs. The interfacial energetics and optoelectronic properties of the perovskite layer grown on a nickel oxide (NiOx) and poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate hole injection interfaces are investigated. The better interface formed between the NiOx/perovskite layers in terms of lower density of traps/defects, as well as more balanced charge carriers in the perovskite layer leading to high recombination yield of carriers are the main reasons for significantly improved device efficiency, photostability of perovskite, and operational stability of PeLEDs.

Journal article

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