|
|
James C
Blakesley
,
Ruy Sebastian
Bonilla
,
Marina
Freitag
,
Alex
Ganose
,
Nicola
Gasparini
,
Pascal
Kaienburg
,
George
Koutsourakis
,
Jonathan D.
Major
,
Jenny
Nelson
,
Nakita K.
Noel
,
Bart
Roose
,
Jae Sung
Yun
,
Simon
Aliwell
,
Pietro
Altermatt
,
Tayebeh
Ameri
,
Virgil
Andrei
,
Ardalan
Armin
,
Diego
Bagnis
,
Jenny
Baker
,
Hamish
Beath
,
Mathieu
Bellanger
,
Philippe
Berrouard
,
Jochen
Blumberger
,
Stuart
Boden
,
Hugo
Bronstein
,
Matthew J.
Carnie
,
Chris
Case
,
Fernando A.
Castro
,
Yi-Ming
Chang
,
Elmer
Chao
,
Tracey M.
Clarke
,
Graeme
Cooke
,
Pablo
Docampo
,
Ken
Durose
,
James
Durrant
,
Marina
Filip
,
Richard H.
Friend
,
Jarvist M.
Frost
,
Elizabeth
Gibson
,
Alexander J.
Gillett
,
Pooja
Goddard
,
Severin
Habisreutinger
,
Martin
Heeney
,
Arthur D.
Hendsbee
,
Louise C.
Hirst
,
Saiful
Islam
,
Imalka
Jayawardena
,
Michael
Johnston
,
Matthias
Kauer
,
Jeff
Kettle
,
Ji-Seon
Kim
,
Dan
Lamb
,
David G.
Lidzey
,
Jihoo
Lim
,
Roderick
Mackenzie
,
Nigel
Mason
,
Iain
Mcculloch
,
Keith
Mckenna
,
Sebastian
Meier
,
Paul
Meredith
,
Graham
Morse
,
John
Murphy
,
Chris
Nicklin
,
Paloma
Ortega-Arriaga
,
Thomas
Osterberg
,
Jay
Patel
,
Anthony
Peaker
,
Moritz
Riede
,
Martyn
Rush
,
James
Ryan
,
David O.
Scanlon
,
Peter
Skabara
,
Franky
So
,
Henry J.
Snaith
,
Ludmilla
Steier
,
Jarla
Thiesbrummel
,
Alessandro
Troisi
,
Craig
Underwood
,
Karsten
Walzer
,
Trystan M.
Watson
,
Michael
Walls
,
Aron
Walsh
,
Lucy D.
Whalley
,
Benedict
Winchester
,
Sam
Stranks
,
Robert
Hoye
Open Access
Abstract: Photovoltaics (PVs) are a critical technology for curbing growing levels of anthropogenic greenhouse gas emissions, and meeting increases in future demand for low-carbon electricity. In order to fulfil ambitions for net-zero carbon dioxide equivalent (CO2eq) emissions worldwide, the global cumulative capacity of solar PVs must increase by an order of magnitude from 0.9 TWp in 2021 to 8.5 TWp by 2050 according to the International Renewable Energy Agency, which is considered to be a highly conservative estimate. In 2020, the Henry Royce Institute brought together the UK PV community to discuss the critical technological and infrastructure challenges that need to be overcome to address the vast challenges in accelerating PV deployment. Herein, we examine the key developments in the global community, especially the progress made in the field since this earlier roadmap, bringing together experts primarily from the UK across the breadth of the photovoltaics community. The focus is both on the challenges in improving the efficiency, stability and levelized cost of electricity of current technologies for utility-scale PVs, as well as the fundamental questions in novel technologies that can have a significant impact on emerging markets, such as indoor PVs, space PVs, and agrivoltaics. We discuss challenges in advanced metrology and computational tools, as well as the growing synergies between PVs and solar fuels, and offer a perspective on the environmental sustainability of the PV industry. Through this roadmap, we emphasize promising pathways forward in both the short- and long-term, and for communities working on technologies across a range of maturity levels to learn from each other.
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Aug 2024
|
|
I09-Surface and Interface Structural Analysis
|
Theodore D. C.
Hobson
,
Luke
Thomas
,
Laurie J,
Phillips
,
Leanne A. H.
Jones
,
Matthew J.
Smiles
,
Christopher H.
Don
,
Pardeep K.
Thakur
,
Huw
Shiel
,
Stephen
Campbell
,
Vincent
Barrioz
,
Vin
Dhanak
,
Tim
Veal
,
Jonathan D.
Major
,
Ken
Durose
Diamond Proposal Number(s):
[31170]
Open Access
Abstract: We explored the in-situ doping of cadmium telluride thin films with indium to produce n-type absorbers as an alternative to the near-universal choice of p-type for photovoltaic devices. The films were grown by close space sublimation from melt-synthesised feedstock. Transfer of the indium during film growth was limited to 0.0014 – 0.014% - unless reducing conditions were used which yielded 14 – 28% efficient transport. While chunks of bulk feedstock were verified as n-type by the hot probe method, carrier type of thin film material was only able to be verified by using hard x-ray photoelectron spectroscopy to determine the Fermi level position within the band gap. The assignment of n-type conductivity was consistent with the rectification behaviour of a p-InP/CdTe:In junction. However, chloride treatment had the effect of compensating n-CdTe:In to near-intrinsic levels. Without chloride, the highest dopant activation was 20% of the chemical concentration of indium, this being for a film having a carrier concentration of n = 2 x 1015 cm-3. However, the activation was often much lower, and compensation due to over-doping with indium and native defects (stoichiometry) are discussed. Results from preliminary bifacial devices comprising Au/P3HT/ZnTe/CdTe:In/CdS/FTO/glass are presented.
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Sep 2023
|
|
I09-Surface and Interface Structural Analysis
|
Christopher H.
Don
,
Thomas P.
Shalvey
,
Matthew J.
Smiles
,
Luke
Thomas
,
Laurie J.
Phillips
,
Theodore D. C.
Hobson
,
Harry
Finch
,
Leanne A. H.
Jones
,
Jack E. N.
Swallow
,
Nicole
Fleck
,
Christopher
Markwell
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Deepnarayan
Biswas
,
Leon
Bowen
,
Benjamin A. D.
Williamson
,
David O.
Scanlon
,
Vinod R.
Dhanak
,
Ken
Durose
,
Tim D.
Veal
,
Jonathan D.
Major
Diamond Proposal Number(s):
[32696]
Open Access
Abstract: Despite the recent success of CdS/Sb2Se3 heterojunction devices, cadmium toxicity, parasitic absorption from the relatively narrow CdS band gap (2.4 eV) and multiple reports of inter-diffusion at the interface forming Cd(S,Se) and Sb2(S,Se)3 phases, present significant limitations to this device architecture. Among the options for alternative partner layers in antimony chalcogenide solar cells, the wide band gap, non-toxic titanium dioxide (TiO2) has demonstrated the most promise. It is generally accepted that the anatase phase of the polymorphic TiO2 is preferred, although there is currently an absence of analysis with regard to phase influence on device performance. This work reports approaches to distinguish between TiO2 phases using both surface and bulk characterization methods. A device fabricated with a radio frequency (RF) magnetron sputtered rutile-TiO2 window layer (FTO/TiO2/Sb2Se3/P3HT/Au) achieved an efficiency of 6.88% and near-record short–circuit current density (Jsc) of 32.44 mA cm−2, which is comparable to established solution based TiO2 fabrication methods that produced a highly anatase-TiO2 partner layer and a 6.91% efficiency device. The sputtered method introduces reproducibility challenges via the enhancement of interfacial charge barriers in multi-phase TiO2 films with a rutile surface and anatase bulk. This is shown to introduce severe S-shaped current–voltage (J–V) distortion and a drastic fill–factor (FF reduction in these devices.
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Jun 2023
|
|
I09-Surface and Interface Structural Analysis
|
Theodore D. C.
Hobson
,
Huw
Shiel
,
Christopher N.
Savory
,
Jack E. N.
Swallow
,
Leanne A. H.
Jones
,
Thomas J.
Featherstone
,
Matthew J.
Smiles
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Bhaskar
Das
,
Chris
Leighton
,
Guillaume
Zoppi
,
Vin R.
Dhanak
,
David O.
Scanlon
,
Tim D.
Veal
,
Ken
Durose
,
Jonathan D.
Major
Diamond Proposal Number(s):
[23160]
Open Access
Abstract: Antimony selenide (Sb2Se3) is a promising absorber material for thin-film
photovoltaics. However, certain areas of fundamental understanding of this material
remain incomplete and this presents a barrier to further efficiency gains. In particular,
recent studies have highlighted the role of majority carrier type and extrinsic doping
in drastically changing the performance of high efficiency devices [1]. Herein, Sndoped
Sb2Se3 bulk crystals are shown to exhibit p-type conductivity using Hall effect
and hot-probe measurements. The measured conductivities are higher than those
achieved through native defects alone, but with a carrier density (up to 7.4 × 1014
cm−3) several orders of magnitude smaller than the quantity of Sn included in the
source material. Additionally, a combination of ultraviolet, X-ray and hard X-ray
photoemission spectroscopies are employed to obtain a non-destructive depth profile of
the valence band maximum, confirming p-type conductivity and indicating a majority
carrier type inversion layer at the surface. Finally, these results are supported by
density functional theory calculations of the defect formation energies in Sn-doped
Sb2Se3, showing a possible limit on the carrier concentration achievable with Sn as
a dopant. This study sheds light on the effectiveness of Sn as a p-type dopant in
Sb2Se3 and highlights avenues for further optimisation of doped Sb2Se3 for solar energy
devices.
|
Sep 2022
|
|
I09-Surface and Interface Structural Analysis
|
Luke
Thomas
,
Theo D. C.
Hobson
,
Laurie J.
Phillips
,
Kieran J.
Cheetham
,
Neil
Tarbuck
,
Leanne A. H.
Jones
,
Matthew J.
Smiles
,
Chris H.
Don
,
Pardeep K.
Thakur
,
Mark
Isaacs
,
Huw
Shiel
,
Stephen
Campbell
,
Vincent
Barrioz
,
Vin
Dhanak
,
Tim
Veal
,
Jonathan D.
Major
,
Ken
Durose
Diamond Proposal Number(s):
[28268]
Open Access
Abstract: This paper is motivated by the potential advantages of higher doping and lower contact barriers in CdTe photovoltaic devices that may be realized by using n- type rather than the conventional p-type solar absorber layers. We present post-growth doping trials for indium in thin polycrystalline CdTe films using diffusion of indium metal and with indium chloride. Chemical concentrations of indium up to 1019 cm-3 were achieved and the films were verified as n-type by hard x-ray photoemission. Post growth chlorine treatment (or InCl3) was found to compensate the n-doping. Trial structures comprising CdS/CdTe:In verified that the doped absorber structures performed as expected both before and after chloride treatment, but it is recognized that this is not an optimum combination. Hence in order to identify how the advantages of n-type absorbers might be fully realized in future work, we also report simulations of a range of p-n junction combinations with n-CdTe, a number of which have the potential for high Voc.
|
Jun 2022
|
|
I09-Surface and Interface Structural Analysis
|
Matthew J.
Smiles
,
Thomas
Shalvey
,
Luke
Thomas
,
Theodore D. C.
Hobson
,
Leanne A. H.
Jones
,
Laurie
Phillips
,
Christopher
Don
,
Thomas
Beesley
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Ken
Durose
,
Jonathan D.
Major
,
Tim
Veal
Diamond Proposal Number(s):
[31170]
Open Access
Abstract: Germanium selenide (GeSe) bulk crystals, thin films and solar cells are investigated with a focus on acceptor-doping with silver (Ag) and the use of an Sb2Se3 interfacial layer. The Ag-doping of GeSe occurred by a stoichiometric melt growth technique that created Ag-doped GeSe bulk crystals. A combination of capacitance voltage measurements, synchrotron radiation photoemission spectroscopy and surface space-charge calculations indicate Ag-doping increases the hole density from 5.2×1015 cm-3 to 1.9×1016 cm-3. The melt-grown material is used as the source for thermally evaporated GeSe films within solar cells. The cell structure with the highest efficiency of 0.260% is FTO/CdS/Sb2Se3/undoped-GeSe/Au compared with solar cells without the Sb2Se3 interfacial layer or with the Ag-doped GeSe.
|
Apr 2022
|
|
I09-Surface and Interface Structural Analysis
|
Huw
Shiel
,
Theodore D. C.
Hobson
,
Oliver S.
Hutter
,
Laurie J.
Phillips
,
Matthew J.
Smiles
,
Leanne A. H.
Jones
,
Thomas J.
Featherstone
,
Jack E. N.
Swallow
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Jonathan D.
Major
,
Ken
Durose
,
Tim D.
Veal
Diamond Proposal Number(s):
[23160]
Open Access
Abstract: Antimony selenide (Sb2
2
Se3
3
) possesses great potential in the field of photovoltaics (PV) due to its suitable properties for use as a solar absorber and good prospects for scalability. Previous studies have reported the growth of a native antimony oxide (Sb2
2
O3
3
) layer at the surface of Sb2
2
Se3
3
thin films during deposition and exposure to air, which can affect the contact between Sb2
2
Se3
3
and subsequent layers. In this study, photoemission techniques were utilized on both Sb2
2
Se3
3
bulk crystals and thin films to investigate the band alignment between Sb2
2
Se3
3
and the Sb2
2
O3
3
layer. By subtracting the valence band spectrum of an in situ cleaved Sb2
2
Se3
3
bulk crystal from that of the atmospherically contaminated bulk crystal, a valence band offset (VBO) of −1.72
−
1.72
eV is measured between Sb2
2
Se3
3
and Sb2
2
O3
3
. This result is supported by a −1.90
−
1.90
eV VBO measured between Sb2
2
O3
3
and Sb2
2
Se3
3
thin films via the Kraut method. Both results indicate a straddling alignment that would oppose carrier extraction through the back contact of superstrate PV devices. This work yields greater insight into the band alignment of Sb2
2
O3
3
at the surface of Sb2
2
Se3
3
films, which is crucial for improving the performance of these PV devices.
|
Jun 2021
|
|
I09-Surface and Interface Structural Analysis
|
Christopher H.
Don
,
Huw
Shiel
,
Theodore D. C.
Hobson
,
Christopher N.
Savory
,
Jack E. N.
Swallow
,
Matthew J.
Smiles
,
Leanne A. H.
Jones
,
Thomas J.
Featherstone
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Ken
Durose
,
Jonathan D.
Major
,
Vinod R.
Dhanak
,
David O.
Scanlon
,
Tim D.
Veal
Diamond Proposal Number(s):
[21431]
Open Access
Abstract: The presence of a lone pair of 5s electrons at the valence band maximum (VBM) of Sb2Se3 and the resulting band alignments are investigated using soft and hard X-ray photoemission spectroscopy in parallel with density functional theory (DFT) calculations. Vacuum-cleaved and exfoliated bulk crystals of Sb2Se3 are analysed using laboratory and synchrotron X-ray sources to acquire high resolution valence band spectra with both soft and hard X-rays. Utilising the photon-energy dependence of different orbital cross-sections and corresponding DFT calculations, the various orbital contributions to the valence band could be identified, including the 5s orbital's presence at the VBM. The ionization potential is also determined and places the VBM at 5.13 eV below the vacuum level, similar to other materials with 5s2 lone pairs, but far above those of related materials without lone pairs of electrons.
|
Aug 2020
|
|
I09-Surface and Interface Structural Analysis
|
Theodore D. C.
Hobson
,
Laurie J
Phillips
,
Oliver S
Hutter
,
Huw
Shiel
,
Jack E. N.
Swallow
,
Christopher N.
Savory
,
Pabitra K
Nayak
,
Silvia
Mariotti
,
Bhaskar
Das
,
Leon
Bowen
,
Leanne A. H.
Jones
,
Thomas J.
Featherstone
,
Matthew J.
Smiles
,
Mark A
Farnworth
,
Guillaume
Zoppi
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Henry J.
Snaith
,
Chris
Leighton
,
David O.
Scanlon
,
Vinod R.
Dhanak
,
Ken
Durose
,
Tim D.
Veal
,
Jonathan D
Major
Diamond Proposal Number(s):
[21431]
Open Access
Abstract: The carrier type of Sb2Se3 was evaluated for both thin films and bulk crystals via a range of complementary techniques. X-ray photoelectron spectroscopy (XPS), hot-probe, hall effect and surface photo-voltage spectroscopy showed material synthesized from Sb2Se3 granulate mate-rial to be n-type with chlorine identified as an unintentional n-type dopant via secondary ion mass spectrometry analysis. The validity of chlorine as a dopant was con-firmed by synthesis of intrinsic crystals from metallic precursors and subsequent n-type doping by the addition of MgCl2. Chlorine was also shown to be a substitutional n-type shallow dopant by density functional theory calculations. TiO2/Sb2Se3 n-n isotype heterojunction solar cells of 7.3% efficiency based are demonstrated with band alignment analyzed via XPS.
|
Mar 2020
|
|
|
|
Thomas J.
Whittles
,
Tim D.
Veal
,
Christopher N.
Savory
,
Peter J.
Yates
,
Philip A. E.
Murgatroyd
,
James T.
Gibbon
,
Max
Birkett
,
Richard J.
Potter
,
Jonathan D.
Major
,
Ken
Durose
,
David O.
Scanlon
,
Vinod R.
Dhanak
Abstract: The earth-abundant semiconductor Cu3BiS3 (CBS) exhibits promising photovoltaic properties and is often considered analogous to the solar absorbers copper indium gallium diselenide (CIGS) and copper zinc tin sulfide (CZTS) despite few device reports. The extent to which this is justifiable is explored via a thorough X-ray photoemission spectroscopy (XPS) analysis: spanning core levels, ionization potential, work function, surface contamination, cleaning, band alignment, and valence-band density of states. The XPS analysis overcomes and addresses the shortcomings of prior XPS studies of this material. Temperature-dependent absorption spectra determine a 1.2 eV direct band gap at room temperature; the widely reported 1.4–1.5 eV band gap is attributed to weak transitions from the low density of states of the topmost valence band previously being undetected. Density functional theory HSE06 + SOC calculations determine the band structure, optical transitions, and well-fitted absorption and Raman spectra. Valence band XPS spectra and model calculations find the CBS bonding to be superficially similar to CIGS and CZTS, but the Bi3+ cations (and formally occupied Bi 6s orbital) have fundamental impacts: giving a low ionization potential (4.98 eV), suggesting that the CdS window layer favored for CIGS and CZTS gives detrimental band alignment and should be rejected in favor of a better aligned material in order for CBS devices to progress.
|
Jul 2019
|
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