Imperial College London

Dr N.J. (Ned) Ekins-Daukes

Faculty of Natural SciencesDepartment of Physics

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+44 (0)20 7594 6675n.ekins-daukes Website

 
 
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Location

 

H1002Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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293 results found

Pearce PM, Halme J, Jiang JY, Ekins-Daukes NJet al., 2024, Efficiency limits and design principles for multi-junction coloured photovoltaics, Energy and Environmental Science, Vol: 17, Pages: 1189-1201, ISSN: 1754-5692

Building-integrated photovoltaics are an emerging technology with the potential to become more widely adopted as the installed capacity of solar photovoltaics (PV) continues to increase. For building and product integration, the ability to produce cells in colours other than the standard black or dark blue appearance of crystalline silicon panels plays an important role in improving the visual appearance and promoting the adoption of PV. However, to maximize power output from limited areas and use resources in the most sustainable way possible, keeping efficiency high is critical; coloured multi-junction solar cells, which can reach higher power conversion efficiencies than single-junction devices, thus become a technology platform of interest. We report the theoretical maximum possible efficiencies for coloured two-terminal solar cells with up to six junctions in the detailed balance limit, with colour produced through reflection of incident Sunlight. A wide range of colours with a relative luminance up to Y = 0.6 can be produced with <20% maximum power loss compared to a black cells. In most cases, except for colours with very high relative luminance Y ≳ 0.85 (i.e. colours which are closer to white), a two-junction coloured cell has a higher limiting efficiency than a black single-junction cell, showing the potential of coloured multi-junction cells for applications where the aesthetics of solar panels play an important role. We find that crystalline silicon provides an excellent platform as the bottom cell in developing two and three-junction coloured cells, for example in combination with perovskites or III-V semiconductor alloys with tuneable bandgaps. In addition to reporting limiting efficiencies, we report the optimal reflectance spectra and bandgap placement for achieving a range of colours, and the trends observed in these variables for colours of varying hue and relative luminance. A numerical optimization method using multi-objective differential evol

Journal article

Hughes KM, Ito M, Vaquero-Stainer A, Ekins-Daukes NJ, Phillips CCet al., 2024, Increasing the two-photon photocurrent saturation limit in a quantum ratchet intermediate band solar cell, Applied Physics Letters, Vol: 124, ISSN: 0003-6951

A quantum ratchet intermediate band solar cell based on a quantum well superlattice is investigated. The design is similar to that of a previously reported device, but it employs a stronger built-in electric field across the heterojunction; therefore, it works at higher illumination intensities before the photocurrent saturates due to photocarrier accumulation screening out the field and causing leveling of the bands. In this present device, saturation of the two-photon photocurrent occurred at a valence-to-intermediate band pulse energy of ∼4 nJ, approximately ten times greater than the previously reported device, making it more suitable for concentrator applications.

Journal article

Herrando M, Wang K, Huang G, Otanicar T, Mousa OB, Agathokleous RA, Ding Y, Kalogirou S, Ekins-Daukes N, Taylor RA, Markides CNet al., 2023, A review of solar hybrid photovoltaic-thermal (PV-T) collectors and systems, Progress in Energy and Combustion Science, Vol: 97, Pages: 1-74, ISSN: 0360-1285

In this paper, we provide a comprehensive overview of the state-of-the-art in hybrid PV-T collectors and the wider systems within which they can be implemented, and assess the worldwide energy and carbon mitigation potential of these systems. We cover both experimental and computational studies, identify opportunities for performance enhancement, pathways for collector innovation, and implications of their wider deployment at the solar-generation system level. First, we classify and review the main types of PV-T collectors, including air-based, liquid-based, dual air–water, heat-pipe, building integrated and concentrated PV-T collectors. This is followed by a presentation of performance enhancement opportunities and pathways for collector innovation. Here, we address state-of-the-art design modifications, next-generation PV cell technologies, selective coatings, spectral splitting and nanofluids. Beyond this, we address wider PV-T systems and their applications, comprising a thorough review of solar combined heat and power (S–CHP), solar cooling, solar combined cooling, heat and power (S–CCHP), solar desalination, solar drying and solar for hydrogen production systems. This includes a specific review of potential performance and cost improvements and opportunities at the solar-generation system level in thermal energy storage, control and demand-side management. Subsequently, a set of the most promising PV-T systems is assessed to analyse their carbon mitigation potential and how this technology might fit within pathways for global decarbonization. It is estimated that the REmap baseline emission curve can be reduced by more than 16% in 2030 if the uptake of solar PV-T technologies can be promoted. Finally, the review turns to a critical examination of key challenges for the adoption of PV-T technology and recommendations.

Journal article

Pusch A, Römer U, Culcer D, Ekins-Daukes NJet al., 2023, Energy Conversion Efficiency of the Bulk Photovoltaic Effect, PRX Energy, Vol: 2

Journal article

Liu M, Romer U, Ekins-Daukes NJ, Lennon Aet al., 2022, Optical analysis of light management for finger designs in CPV systems, PROGRESS IN PHOTOVOLTAICS, Vol: 30, Pages: 1219-1227, ISSN: 1062-7995

Journal article

Tabernig SW, Soeriyadi AH, Romer U, Pusch A, Lamers D, Juhl MK, Payne DNR, Nielsen MP, Polman A, Ekins-Daukes NJet al., 2022, Avoiding Shading Losses in Concentrator Photovoltaics Using a Soft-Imprinted Cloaking Geometry, IEEE JOURNAL OF PHOTOVOLTAICS, Vol: 12, Pages: 1116-1127, ISSN: 2156-3381

Journal article

Li J, Huang J, Ma F, Sun H, Cong J, Privat K, Webster RF, Cheong S, Yao Y, Chin RL, Yuan X, He M, Sun K, Li H, Mai Y, Hameiri Z, Ekins-Daukes NJ, Tilley RD, Unold T, Green MA, Hao Xet al., 2022, Unveiling microscopic carrier loss mechanisms in 12% efficient Cu<inf>2</inf>ZnSnSe<inf>4</inf> solar cells, Nature Energy, Vol: 7, Pages: 754-764

Understanding carrier loss mechanisms at microscopic regions is imperative for the development of high-performance polycrystalline inorganic thin-film solar cells. Despite the progress achieved for kesterite, a promising environmentally benign and earth-abundant thin-film photovoltaic material, the microscopic carrier loss mechanisms and their impact on device performance remain largely unknown. Herein, we unveil these mechanisms in state-of-the-art Cu2ZnSnSe4 (CZTSe) solar cells using a framework that integrates multiple microscopic and macroscopic characterizations with three-dimensional device simulations. The results indicate the CZTSe films have a relatively long intragrain electron lifetime of 10–30 ns and small recombination losses through bandgap and/or electrostatic potential fluctuations. We identify that the effective minority carrier lifetime of CZTSe is dominated by a large grain boundary recombination velocity (~104 cm s−1), which is the major limiting factor of present device performance. These findings and the framework can greatly advance the research of kesterite and other emerging photovoltaic materials.

Journal article

Rohr JA, Sartor BE, Duenow JN, Qin Z, Meng J, Lipton J, Maclean SA, Romer U, Nielsen MP, Zhao S, Kong J, Reese MO, Steiner MA, Ekins-Daukes NJ, Taylor ADet al., 2022, Identifying optimal photovoltaic technologies for underwater applications, ISCIENCE, Vol: 25

Journal article

Nielsen MP, Pusch A, Sazzad MH, Pearce PM, Reece PJ, Ekins-Daukes NJet al., 2022, Thermoradiative Power Conversion from HgCdTe Photodiodes and Their Current-Voltage Characteristics, ACS PHOTONICS, Vol: 9, Pages: 1535-1540, ISSN: 2330-4022

Journal article

Gholizadeh EM, Prasad SKK, Gillan L, Nielsen MP, Ekins-Daukes NJ, McCamey DR, Tayebjee MJY, Schmidt TWet al., 2021, Singlet and Triplet Exciton Dynamics of Violanthrone, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 125, Pages: 22464-22471, ISSN: 1932-7447

Journal article

Tang S, Bing J, Zheng J, Tang J, Li Y, Mayyas M, Cho Y, Jones TW, Yang TC-J, Yuan L, Tebyetekerwa M, Nguyen HT, Nielsen MP, Ekins-Daukes NJ, Kalantar-Zadeh K, Wilson GJ, McKenzie DR, Huang S, Ho-Baillie AWYet al., 2021, Complementary bulk and surface passivations for highly efficient perovskite solar cells by gas quenching, CELL REPORTS PHYSICAL SCIENCE, Vol: 2

Journal article

Jiang Y, Nielsen MP, Baldacchino AJ, Green MA, McCamey DR, Tayebjee MJY, Schmidt TW, Ekins-Daukes NJet al., 2021, Singlet fission and tandem solar cells reduce thermal degradation and enhance lifespan, PROGRESS IN PHOTOVOLTAICS, Vol: 29, Pages: 899-906, ISSN: 1062-7995

Journal article

Choi TH, Brindley H, Ekins-Daukes N, Escobar Ret al., 2021, Developing automated methods to estimate spectrally resolved direct normal irradiance for solar energy applications, Renewable Energy, Vol: 173, Pages: 1070-1086, ISSN: 0960-1481

We describe four schemes designed to estimate spectrally resolved direct normal irradiance (DNI) formulti-junction concentrator photovoltaic systems applications. The schemes have increasing levels ofcomplexity in terms of aerosol and circumsolar irradiance (CSI) treatment, ranging from a climatologicalaerosol classification with no account of CSI, to an approach which includes explicit aerosol typing andtype dependent CSI contribution. When tested against ground-based broadband and spectral measurements at five sites spanning a range of aerosol conditions, the most sophisticated scheme yields anaverage bias of þ 0:068%, well within photometer calibration uncertainties. The average spread of erroris 2:5%. These statistics are markedly better than the climatological approach, which carries an averagebias of 1:76% and a spread of 4%. They also improve on an intermediate approach which uses Angstrom€exponents to estimate the spectral variation in aerosol optical depth across the solar energy relevantwavelength domain. This approach results in systematic under and over-estimations of DNI at short andlong wavelengths respectively. Incorporating spectral CSI particularly benefits sites which experience asignificant amount of coarse aerosol. All approaches we describe use freely available reanalyses andsoftware tools, and can be easily applied to alternative aerosol measurements, including those fromsatellite.

Journal article

Yamaguchi M, Dimroth F, Geisz JF, Ekins-Daukes NJet al., 2021, Multi-junction solar cells paving the way for super high-efficiency, JOURNAL OF APPLIED PHYSICS, Vol: 129, ISSN: 0021-8979

Journal article

Pusch A, Bremner SP, Tayebjee MJY, Daukes NJEet al., 2021, Microscopic reversibility demands lower open circuit voltage in multiple exciton generation solar cells, APPLIED PHYSICS LETTERS, Vol: 118, ISSN: 0003-6951

Journal article

Sogabe T, Hung C-Y, Tamaki R, Tomic S, Yamaguchi K, Ekins-Daukes N, Okada Yet al., 2021, Experimental demonstration of energy-transfer ratchet intermediate-band solar cell, COMMUNICATIONS PHYSICS, Vol: 4, ISSN: 2399-3650

Journal article

Zhou Z, Jiang Y, Ekins-Daukes N, Keevers M, Green MAet al., 2021, Optical and Thermal Emission Benefits of Differently Textured Glass for Photovoltaic Modules, IEEE JOURNAL OF PHOTOVOLTAICS, Vol: 11, Pages: 131-137, ISSN: 2156-3381

Journal article

Steiner MA, France RM, Buencuerpo J, Geisz JF, Nielsen MP, Pusch A, Olavarria WJ, Young M, Ekins-Daukes NJet al., 2021, High Efficiency Inverted GaAs and GaInP/GaAs Solar Cells With Strain-Balanced GaInAs/GaAsP Quantum Wells, ADVANCED ENERGY MATERIALS, Vol: 11, ISSN: 1614-6832

Journal article

Steiner MA, France RM, Buencuerpo J, Geisz JF, Nielsen MP, Pusch A, Olavarria WJ, Young M, Ekins-Daukes NJet al., 2021, 32.9% efficient tandem solar cell with strain-balanced GaInAs/GaAsP quantum wells, 48th IEEE Photovoltaic Specialists Conference (PVSC), Publisher: IEEE, Pages: 1084-1085, ISSN: 0160-8371

Conference paper

Liu M, Romer U, Ekins-Daukes NJ, Lennon Aet al., 2021, Optical Analysis of Secondary Optics for Solar Concentrators with a View to Optimising Cell Metallisation, 48th IEEE Photovoltaic Specialists Conference (PVSC), Publisher: IEEE, Pages: 2270-2272, ISSN: 0160-8371

Conference paper

Liu M, Soeriyadi AH, Song N, Hsiao PC, Romer U, Ekins-Daukes N, Lennon Aet al., 2020, Formation Mechanism of Cu-based Ohmic Contacts for GaAs Solar Cells, Pages: 0829-0832, ISSN: 0160-8371

Copper contacts on GaAs are gaining increasing attention for low-cost high-efficiency solar cell devices. Cu/Ge/Pd and Cu/Pt/Ti/Pt contacts have been reported to achieve low specific contact resistivities in the range of 10_{-5}\ \mathrm{\Omega} \text{cm}_{2}. A preliminary study for the formation mechanism of these two Cu-based structures on both n-type and p-type GaAs substrates subjected to different thermal annealing conditions is reported. The results indicate that the formation of the Cu3Ge and PdGaxAsy compounds in conjunction with the creation of Ga vacancies are among the reasons for low contact resistance for n-GaAs. The high work function of Pt and high melting temperature of both Pt and Ti help to reduce the contact resistance for p-GaAs.

Conference paper

Rodriguez AS, de Santana T, MacGill I, Ekins-Daukes NJ, Reinders Aet al., 2020, A feasibility study of solar PV-powered electric cars using an interdisciplinary modeling approach for the electricity balance, CO2 emissions, and economic aspects: The cases of The Netherlands, Norway, Brazil, and Australia, PROGRESS IN PHOTOVOLTAICS, Vol: 28, Pages: 517-532, ISSN: 1062-7995

Journal article

Zeng Y, Sun K, Huang J, Nielsen MP, Ji F, Sha C, Yuan S, Zhang X, Yan C, Liu X, Deng H, Lai Y, Seidel J, Ekins-Daukes N, Liu F, Song H, Green M, Hao Xet al., 2020, Quasi-Vertically-Orientated Antimony Sulfide Inorganic Thin-Film Solar Cells Achieved by Vapor Transport Deposition, ACS APPLIED MATERIALS & INTERFACES, Vol: 12, Pages: 22825-22834, ISSN: 1944-8244

Journal article

Aghaei M, Nitti M, Ekins-Daukes NJ, Reinders AHMEet al., 2020, Simulation of a Novel Configuration for Luminescent Solar Concentrator Photovoltaic Devices Using Bifacial Silicon Solar Cells, APPLIED SCIENCES-BASEL, Vol: 10

Journal article

Liu M, Soeriyadi AH, Song N, Hsiao P-C, Romer U, Ekins-Daukes N, Lennon Aet al., 2020, Formation Mechanism of Cu-based Ohmic Contacts for GaAs Solar Cells, 47th IEEE Photovoltaic Specialists Conference (PVSC), Publisher: IEEE, Pages: 829-832, ISSN: 0160-8371

Conference paper

Pusch A, Dubajic M, Ekins-Daukes NJ, Bremner Set al., 2020, Fundamental Aspects of Hot Carrier Solar Cell Operation, 47th IEEE Photovoltaic Specialists Conference (PVSC), Publisher: IEEE, Pages: 2227-2232, ISSN: 0160-8371

Conference paper

Ekins-Daukes NJ, Sazzad MH, Al Kiyumi L, Nielsen MP, Reece P, Mellor A, Green MA, Pusch Aet al., 2020, Generating Power at Night Using a Thermoradiative Diode, How is this Possible?, 47th IEEE Photovoltaic Specialists Conference (PVSC), Publisher: IEEE, Pages: 2214-2218, ISSN: 0160-8371

Conference paper

Pearce P, Sayre L, Johnson A, Hirst L, Ekins-Daukes Net al., 2020, Design of photonic light-trapping structures for ultra-thin solar cells, Conference on Physics, Simulation, and Photonic Engineering of Photovoltaic Devices IX, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X

Conference paper

Pusch A, Gordon JM, Mellor A, Krich JJ, Ekins-Daukes NJet al., 2019, Fundamental Efficiency Bounds for the Conversion of a Radiative Heat Engine's Own Emission into Work, PHYSICAL REVIEW APPLIED, Vol: 12, ISSN: 2331-7019

Journal article

Gentillon P, Singh S, Lakshman S, Zhang Z, Paduthol A, Ekins-Daukes NJ, Chan QN, Taylor RAet al., 2019, A comprehensive experimental characterisation of a novel porous media combustion-based thermophotovoltaic system with controlled emission, APPLIED ENERGY, Vol: 254, ISSN: 0306-2619

Journal article

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