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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
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I07-Surface & interface diffraction
|
Anna
Jungbluth
,
Eunkyung
Cho
,
Alberto
Privitera
,
Kaila M.
Yallum
,
Pascal
Kaienburg
,
Andreas E.
Lauritzen
,
Thomas
Derrien
,
Sameer V.
Kesava
,
Irfan
Habib
,
Saied Md
Pratik
,
Natalie
Banerji
,
Jean-Luc
Brédas
,
Veaceslav
Coropceanu
,
Moritz
Riede
Diamond Proposal Number(s):
[26630]
Open Access
|
Jun 2024
|
|
I07-Surface & interface diffraction
|
Abstract: Organic photovoltaics (OPV) provide an environmentally friendly solution to meet the ever-increasing global energy demand, therefore understanding how to maximize their efficiency is crucial. This work seeks to demonstrate a suite of in situ X-ray techniques for characterising the morphology of OPV made via vacuum thermal evaporation. The microstructure of OPV governs device performance and fabrication processes are a key element of tuning morphological properties. Strategies for tuning microstructure on this project include annealing processes and templating layers. To track how these processing conditions impact the morphology of the film growth, in situ grazing incidence wide angle X-ray scattering (GIWAXS) and resonant soft X-ray scattering (RSoXS) are employed on a set of high performing molecules used in OPV, including DCV5T and DTDCPB. In situ GIWAXS taken during film growth is used to show how the molecular orientation changes as a function of distance from a templating layer interface. In situ RSoXS will be taken with different annealing processes being performed, to show the evolution of mixing behaviour of two energetically offset molecular species when thermally or solvent vapour annealed. It has previously been shown that thermal annealing has a positive correlation with domain size in a bulk heterojunction mixture.
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Mar 2024
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|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[26630]
Open Access
Abstract: The performance of organic solar cells is strongly governed by the properties of the photovoltaic active layer. In particular, the energetics at the donor (D)–acceptor (A) interface dictate the properties of charge transfer (CT) states and limit the open-circuit voltage. More generally, energetic landscapes in thin films are affected by intermolecular, e.g., van der Waals, dipole, and quadrupole, interactions that vary with D:A mixing ratio and impact energy levels of free charges (ionization energy, electron affinity) and excitons (singlet, CT states). Disentangling how different intermolecular interactions impact energy levels and support or hinder free charge generation is still a major challenge. In this work, we investigate interface energetics of bulk heterojunctions via sensitive external quantum efficiency measurements and by varying the D:A mixing ratios of ZnPc or its fluorinated derivatives and C60. With increasing donor fluorination, the energetic offset between FxZnPc and C60 reduces. Moving from large to low offset systems, we find qualitatively different trends in device performances with D:C60 mixing ratios. We rationalize the performance trends via changes in the energy levels that govern exciton separation and voltage losses. We do so by carefully analyzing shifts and broadening sEQE spectra on a linear and logarithmic scale. Linking this analysis with molecular properties and device performance, we comment on the impact of charge–quadrupole interactions for CT dissociation and free charge generation in our D:C60 blends. With this, our work (1) demonstrates how relatively accessible characterization techniques can be used to probe energy levels and (2) addresses ongoing discussions on future molecular design and optimal D–A pairing for efficient CT formation and dissociation.
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Jun 2023
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I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[20426]
Open Access
Abstract: We report on the characterization of the growth of vacuum-deposited zinc phthalocyanine (ZnPc) thin films on glass through a combination of in situ grazing incidence x-ray scattering, x-ray reflectivity, and atomic force microscopy. We found that the growth at room temperature proceeds via the formation of two structurally unique substrate-induced interfacial layers, followed by the growth of the
γ
-ZnPc polymorph thereafter (thickness
≈
1.0
nm). As the growth of the bulk
γ
-ZnPc progresses, a substantial out-of-plane lattice strain (
≈
15
%
relative to
γ
-ZnPc powder) is continually relaxed during the thin film growth. The rate of strain relaxation was slowed after a thickness of
≈
13
nm, corresponding to the transition from layer growth to island growth. The findings reveal the real-time microstructural evolution of ZnPc and highlight the importance of substrate-induced strain on thin film growth.
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Mar 2022
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I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[26630]
Open Access
Abstract: Organic solar cells (OSCs), also known as organic photovoltaics (OPVs), are an emerging solar cell technology composed of carbon-based, organic molecules, which convert energy from the sun into electricity. Key for their performance is the microstructure of the light-absorbing organic bulk heterojunction. To study this, organic solar films composed of both fullerene C60 as electron acceptor and different mole percentages of di-[4-(N,N-di-p-tolyl-amino)-phenyl]-cyclohexane (TAPC) as electron donor were evaporated in vacuum in different mixing ratios (5, 50 and 95 mol%) on an ITO-coated glass substrate held at room temperature and at 110 °C. The microstructure of the C60: TAPC heterojunction was studied by grazing incidence wide angle X-ray scattering to understand the effect of substrate heating. By increasing the substrate temperature from ambient to 110 °C, it was found that no significant change was observed in the crystal size for the C60: TAPC concentrations investigated in this study. In addition to the variation done in the substrate temperature, the variation of the mole percent of the donor (TAPC) was studied to conclude the effect of both the substrate temperature and the donor concentration on the microstructure of the OSC films. Bragg peaks were attributed to C60 in the pure C60 sample and in the blend with low donor mole percentage (5%), but the C60 peaks became nondiscernible when the donor mole percentage was increased to 50% and above, showing that TAPC interrupted the formation of C60 crystals.
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Apr 2021
|
|
I07-Surface & interface diffraction
|
Alberto
Privitera
,
Ross
Warren
,
Giacomo
Londi
,
Pascal
Kaienburg
,
Junjie
Liu
,
Andreas
Sperlich
,
Andreas E.
Lauritzen
,
Oliver
Thimm
,
Arzhang
Ardavan
,
David
Beljonne
,
Moritz
Riede
Diamond Proposal Number(s):
[20426]
Open Access
Abstract: We use the electron spin as a probe to gain insight into the mechanism of molecular doping in a p-doped zinc phthalocyanine host across a broad range of temperatures (80–280 K) and doping concentrations (0–5 wt% of F6-TCNNQ). Electron paramagnetic resonance (EPR) spectroscopy discloses the presence of two main paramagnetic species distinguished by two different g-tensors, which are assigned based on density functional theory calculations to the formation of a positive polaron on the host and a radical anion on the dopant. Close inspection of the EPR spectra shows that radical anions on the dopants couple in an antiferromagnetic manner at device-relevant doping concentrations, thereby suggesting the presence of dopant clustering, and that positive polarons on the molecular host move by polaron hopping with an activation energy of 5 meV. This activation energy is substantially smaller than that inferred from electrical conductivity measurements (∼233 meV), as the latter also includes a (major) contribution from charge-transfer state dissociation. It emerges from this study that probing the electron spin can provide rich information on the nature and dynamics of charge carriers generated upon doping molecular semiconductors, which could serve as a basis for the design of the next generation of dopant and host materials.
|
Feb 2021
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[20426, 24871]
Open Access
Abstract: The real-time morphological evolution of vacuum deposited α-sexithiophene (α-6T) on a weakly interacting (glass) substrate at ambient temperature is reported. In-situ grazing incidence small angle X-ray scattering (GISAXS) enabled the observation of nanoscale aggregates while in-situ grazing incidence wide angle scattering (GIWAXS) allowed the study of the molecular-scale morphology. The in-situ GISAXS measurements revealed that the α-6T growth proceeds via a Stranski-Krastanov mode, whereby 2-4 complete monolayers are deposited followed by subsequent layers formed via island growth. In-situ GIWAXS also showed the evolution of the polymorph composition during the thin film growth. Initially the disordered β-phase and the low-temperature (LT) phase are deposited in nearly equal proportion until a thickness of 8 nm whereby the LT-phase begins to dominate until a final α-6T thickness of 50 nm where the scattering intensity of the LT-phase is more than double that of the β-phase. The change in polymorph composition coincided with an increase in the LT-phase d-spacing, indicating a lattice strain relief as the thin film moves from surface to bulk mediated growth. The GISAXS findings were confirmed through direct imaging using ex-situ atomic force microscopy (AFM) at various thicknesses revealing the existence of both initial monolayers and intermediate and final island morphologies. The findings reveal the real-time morphological evolution of α-6T across both the molecular scale and the nanoscale and highlight the role of strain in polymorph growth. Due to the importance of thin film microstructure in device performance, it is expected that these results will aid in the development of the structure-property relationships necessary to realise the full potential of organic electronics.
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May 2020
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[18016]
Abstract: The quenching of excitons in organic solar cells can play a significant role in limiting their power conversion efficiency (PCE). In this article, we investigate the effect of a thin layer of hexapropyltruxene inserted at the interface between the electron donor boron subphthalocyanine chloride (SubPc) and its underlying hole contact in planar heterojunction solar cells. We find that a 3.8 nm hexapropyltruxene interlayer between the molybdenum oxide (MoOx) hole contact and SubPc is sufficient to improve PCE in SubPc/C60 fullerene solar cells from 2.6% to 3.0%, a ∼20% performance improvement. While the absorption stays roughly the same, the comparison of external and internal quantum efficiencies reveals a significant increase in SubPc's contribution to the current for light with wavelengths between 520 and 600 nm. Microstructure and surface morphology assessed with in situ Grazing-Incidence Wide-Angle X-Ray Scattering (GIWAXS) and Atomic Force Microscopy (AFM), are evaluated alongside in situ spectroscopic ellipsometry, and photoluminescence measurements. The microstructural investigations demonstrate changes to the surface and bulk of SubPc grown atop a hexapropyltruxene interlayer indicating that the latter acts as a template layer in a similar way as MoOx. However, the improvement in PCE is found to be mainly via reduced exciton quenching at the MoOx contact with the insertion of the hexapropyltruxene layer.
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Apr 2020
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|
E02-JEM ARM 300CF
|
Diamond Proposal Number(s):
[22207]
Abstract: Confining electric fields to a nanoscale region is challenging yet crucial for applications such as high resolution probing of electrical properties of materials and electric-field manipulation of nanoparticles. State-of-the-art techniques involving atomic force microscopy typically have a lateral resolution limit of tens of nanometers due to limitations in the probe geometry and stray electric fields that extend over space. Engineering the probes is the most direct approach to improving this resolution limit. However, current methods to fabricate high-resolution probes, which can effectively confine the electric fields laterally involve expensive and sophisticated probe manipulation, which has limited the use of this approach. Here, we demonstrate that nanoscale phase switching of configurable thin films on probes can result in high-resolution electrical probes. These configurable coatings can be both germanium-antimony-tellurium (GST) as well as amorphous-carbon, materials known to undergo electric field-induced non-volatile, yet reversible switching. By forming a localized conductive filament through phase transition, we demonstrate a spatial resolution of electrical field beyond the geometrical limitations of commercial platinum probes (i.e. an improvement of ~48%). We then utilize these confined electric fields to manipulate nanoparticles with single nanoparticle precision via dielectrophoresis. Our results advance the field of nanomanufacturing and metrology with direct applications for pick and place assembly at the nanoscale.
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Jan 2020
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