I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[30708, 30349]
Open Access
Abstract: Coordination nanosheets (CONASHs) or conjugated metal organic frameworks (MOFs) with distinctive metal-organic bonding structures exhibit promise for electronics, sensing, and energy storage. Porous Nickel-Benzene hexathiol complex (Ni-BHT) with noteworthy conductivity was first reported a decade ago, and recent synthetic modifications produced non-porous Ni-BHT with enhanced conductivity (≈50 S cm−1). Here the charge transport physics of such non-porous Ni-BHT films are studied with even higher conductivity (≈112 S cm−1). In contrast to the thermally activated electrical conductivity, thermoelectric measurements suggest an intrinsic metallic nature of Ni-BHT. It is shown that it is possible to tune the Fermi level and carrier polarity in Ni-BHT by electrolyte gating; gating is initially governed by the formation of an interfacial, electric double layer and then evolves into an electrochemical (de)doping process. These findings not only contribute to a deeper understanding of charge transport in CONASHs, but also show that Fermi level tuning is an effective approach for enhancing the thermoelectric performance of CONASHs.
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Jun 2025
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I07-Surface & interface diffraction
I09-Surface and Interface Structural Analysis
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Alessandro J.
Mirabelli
,
Birgit
Kammlander
,
Yang
Lu
,
Rahul Mahavir
Varma
,
Qichun
Gu
,
Karen
Radetzky
,
Thomas A.
Selby
,
Tianjun
Liu
,
Stefania
Riva
,
Zimu
Wei
,
Tien-Lin
Lee
,
Jonathan
Rawle
,
Hakan
Rensmo
,
Miguel
Anaya
,
Ute B.
Cappel
,
Samuel D.
Stranks
Diamond Proposal Number(s):
[30043, 32266, 30838, 33096]
Open Access
Abstract: To commercialize lead halide perovskites as light-emitting diodes (LEDs), the operational device lifetime needs to be drastically improved. For this to be achieved, an understanding of degradation behavior under bias is crucial. Herein, we perform operando measurements of the structural, chemical, and electronic changes using synchrotron-based grazing-incidence wide-angle X-ray scattering and hard X-ray photoelectron spectroscopy on full-stack deep blue mixed bromide/chloride lead halide perovskite LEDs. While a clear drop in optoelectronic performance is recorded under electrical bias, the accompanying X-ray scattering data reveals only minor changes in structural properties. However, photoelectron spectroscopy reveals substantial chemical changes at the electron-injecting interface after bias is applied, including the formation of unwanted metallic lead and a new chlorine species that is not in the perovskite structure. These operando approaches give important structural and interfacial perspectives to reveal the degradation mechanisms in these LEDs and highlight the need to address the top electron-injecting interface to realize step-changes in operational stability.
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Jun 2025
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[30708, 30349]
Open Access
Abstract: We have studied the charge transport physics of high-quality conducting coordination nanosheets films based on the benchmark material copper benzenehexathiol (CuBHT) by measuring multiple thermoelectric and magnetotransport coefficients on the same film. The films exhibit a metallic temperature dependence of the conductivity over a wide temperature range, but below 15 kelvin charge transport becomes dominated by weak localization and electron-electron interactions. Temperature-dependent Hall, Seebeck, and Nernst measurements consistently indicate the existence of ambipolar transport characteristics in CuBHT. A two-band analysis has been used to extract transport parameters for electron and hole carriers as a function of temperature. The results show that contributions from electron and hole conduction in CuBHT are of comparable magnitude, revealing the complexity of charge transport and allowing one to identify strategies for enhancing the thermoelectric transport coefficients of such conducting coordination nanosheets.
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Apr 2025
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I07-Surface & interface diffraction
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Jiawei
Chen
,
Kangyu
Ji
,
Linjie
Dai
,
Hengyang
Xiang
,
Zhongzheng
Yu
,
Affan N.
Iqbal
,
Jian
Wang
,
Xingyue
Ma
,
Renjun
Guo
,
Miguel
Anaya
,
Xiufeng
Song
,
Yang
Lu
,
Yu-Hsien
Chiang
,
Weijin
Li
,
Yalong
Shen
,
Xiyu
Luo
,
Alessandro
Mirabelli
,
Yuanzhuang
Cheng
,
Xinrui
Chen
,
Dongxin
Ma
,
Zhiyong
Fan
,
Yurong
Yang
,
Lian
Duan
,
Samuel D.
Stranks
,
Haibo
Zeng
Diamond Proposal Number(s):
[30575]
Open Access
Abstract: Traditional white light-emitting diodes operate by exciting phosphors using blue light-emitting diodes, leading to the absence of specific colour bands compared with the visible light region of the sunlight spectrum (400–780 nm), and excess blue light increases the risk of harmful effects on ecosystems and organisms. Here, we precisely design and regulate heterophase γ/δ-CsPb(I/Cl)3 at the nanoscale for uniform heterophase distribution, balanced flow of charges and tunable spectrum. Then, γ/δ-CsPb(I/Cl)3 directly excited by electricity shows full-spectrum white electroluminescence covering 400–780 nm with standard Commission Internationale de l’Eclairage coordinates of (0.33, 0.33), a Colour Rendering Index of 95, a Correlated Colour Temperature of 5829 K and a Delta u,v of −3 × 10−4, accompanied with balanced white light composition (Melanopic ratio = 1.004). The match indices of such five core indicators to standard sunlight reach 100%, 95% (97% for R9), 99.5%, 99.97% and 99.6%, respectively, far ahead of as-fabricated commercial white light-emitting diodes.
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Apr 2025
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I07-Surface & interface diffraction
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Rahul A.
Nambiar
,
David P.
Mcmeekin
,
Manuel
Kober Czerny
,
Joel A.
Smith
,
Margherita
Taddei
,
Pietro
Caprioglio
,
Amit
Kumar
,
Benjamin W.
Putland
,
Junke
Wang
,
Karim A.
Elmestekawy
,
Akash
Dasgupta
,
Seongrok
Seo
,
M. Greyson
Christoforo
,
Jin
Yao
,
Daniel J.
Graham
,
Laura M.
Herz
,
David
Ginger
,
Henry J.
Snaith
Diamond Proposal Number(s):
[33462]
Open Access
Abstract: Vacuum deposition of metal halide perovskite is a scalable and adaptable method. In this study, we adopt sequential evaporation to form the perovskite layer and reveal how the relative humidity during the annealing step, impacts its crystallinity and the photoluminescence quantum yield (PLQY). By controlling the humidity, we achieved a significant enhancement of 50 times in PLQY from 0.12% to 6%. This improvement corresponds to an increase in implied open-circuit voltage (Voc) of over 100 meV. We investigate the origin of this enhanced PLQY by combining structural, chemical and spectroscopic methods. Our results show that annealing in a controlled humid environment improves the organic and inorganic halides' interdiffusion throughout the bulk, which in turn significantly reduces non-radiative recombination both in the bulk and at the interfaces with the charge transport layers, which enhanced both the attainable open-circuit voltage and the charge carrier diffusion length. We further demonstrate that the enhanced intermixing results in fully vacuum-deposited FA0.85Cs0.15Pb(IxCl1−x)3 p-i-n perovskite solar cells (PSCs) with a maximum power point tracked efficiency of 21.0% under simulated air mass (AM) 1.5G 100 mW cm−2 irradiance. Additionally, controlled humidity annealed PSCs exhibit superior stability when aged under full spectrum simulated solar illumination at 85 °C and in open-circuit conditions.
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Mar 2025
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[36553]
Open Access
Abstract: The efficiency of organic solar cells has raised drastically in the past years. However, there is an undeniable lack of hole transport layers that can provide high carrier selectivity, low defect density, and high processing robustness, simultaneously. In this work, this issue is addressed by studying defect generation and surface passivation of nickel oxide (NiOx). It is revealed that the generation of high oxidation state species on NiOx surface lowers contact resistance but hinders charge extraction when employed as transport layer in organic solar cells. By using them as coordination centers, a straightforward surface modification strategy is implemented using (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) that enhances charge extraction and increases the solar cell efficiency from 11.46% to 17.12%. Additionally, the robustness of this modification across different deposition methods of the carbazole molecule is demonstrated. Finally, by fine-tuning the Fermi level using various carbazole-based molecules, and in particular with ((4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB), a power conversion efficiency of 17.29% is achieved, with an outstanding combination of a VOC of 0.888 V and a fill factor of 80%.
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Jan 2025
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I07-Surface & interface diffraction
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Feray
Ünlü
,
Alejandra
Florez
,
Keely
Dodd-Clements
,
Lennart K.
Reb
,
Michael
Götte
,
Matthias
Grosch
,
Fengning
Yang
,
Senol
Öz
,
Florian
Mathies
,
Sanjay
Mathur
,
Daniel
Ramirez
,
Franklin
Jaramillo
,
Eva
Unger
Diamond Proposal Number(s):
[36427]
Open Access
Abstract: Halide perovskite solar cells are approaching commercialization, with solution processing emerging as a key method for large-scale production. This study introduces a significant advancement: using non-toxic solvents like water and alcohol in perovskite precursor inks facilitated by the protic ionic liquid methylammonium propionate (MAP). MAP effectively dissolves perovskite precursors such as lead acetate and methylammonium iodide, enabling the first stable water-based perovskite precursor ink suitable for one-step slot-die coating. This new ink formulation contrasts with conventional dimethylformamide (DMF) and dimethylsulfoxide (DMSO)-based inks, as evidenced by in-situ grazing incidence wide-angle X-ray scattering (GIWAXS), which revealed an intermediate-free liquid-to-solid transition. In-situ mass spectrometry also showed that organic molecules evaporate during annealing, resulting in a crystalline perovskite phase. Optimization of the solvent mixture to H2O/IPA/MAP enabled successful slot-die coating, yielding perovskite solar cells with an efficiency of up to 10%. This eco-friendly ink reduces toxicity and environmental impact compared to DMF-based inks, offering a longer shelf life and the possibility of using the ink in ambient conditions. This pioneering work represents the first report of a water-based green ink formulation for one-step thin film coating at room-temperature conditions by slot-die coating, highlighting its potential for sustainable commercial applications.
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Jan 2025
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[32266]
Abstract: Organic solar cells (OSCs) are attracting significant attention due to their low cost, lightweight, and flexible nature. The introduction of nonfullerene acceptors (NFAs) has propelled OSC development into a transformative era. However, the limited availability of wide band gap polymer donors for NFAs poses a critical challenge, hindering further advancements. This study examines the role of developed wide band gap halogenated pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (PPD)-based polymers, in combination with the Y6 nonfullerene acceptor, in bulk heterojunction (BHJ) OSCs. We first focus on the electronic and absorbance modifications brought about by halogen substitution in PPD-based polymers, revealing how these adjustments influence the HOMO/LUMO energy levels and, subsequently, photovoltaic performance. Despite the increased Voc of halogenated polymers due to the optimal band alignment, power conversion efficiencies (PCEs) were decreased due to suboptimal blend morphologies. We second implemented PPD as a solid additive to PM6:Y6, forming ternary OSCs and further improving the PCE. The study provides a nuanced understanding of the interplay between molecular design, device morphology, and OSC performance and opens insights for future research to achieve an optimal balance between band alignment and favorable blend morphology for high-efficiency OSCs.
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Jan 2025
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I07-Surface & interface diffraction
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Matteo
Degani
,
Riccardo
Pallotta
,
Giovanni
Pica
,
Masoud
Karimipour
,
Alessandro
Mirabelli
,
Kyle
Frohna
,
Miguel
Anaya
,
Tianyu
Xu
,
Chang-Qi
Ma
,
Samuel D.
Stranks
,
Monica Lira
Cantù
,
Giulia
Grancini
Diamond Proposal Number(s):
[32266]
Open Access
Abstract: Interface engineering using self-assembled 2D perovskite interfaces is a consolidated route to efficient and durable perovskite solar cells. Whether the 2D perovskite forms a homogeneous conformal layer or is heterogeneously distributed on the surface, interface defects are passivated, leading to a general improvement in the device's open circuit voltage (VOC) and stability. Here, an innovative strategy is developed for manipulating the composition of the 2D/3D perovskite interface that results in the formation of a gradient halide distribution, which extends from the surface to the bulk. The use of a bromide-based 2D perovskite triggers a progressive Br/I exchange, affecting not only the surface but also the perovskite underneath. As a result, not only the device VOC improve, as expected, but also the photogenerated current is boosted, leading to a device efficiency of up to 24.4%. Such mixed halide gradient effectively passivates surface and bulk defects making the perovskite active layer more efficient and robust, as demonstrated by the superior device stability showing zero losses in performances upon 36 days (more than 800 h) test in outdoor conditions, those ones relevant for a marketable product.
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Dec 2024
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I07-Surface & interface diffraction
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Benjamin M.
Gallant
,
Philippe
Holzhey
,
Joel A.
Smith
,
Saqlain
Choudhary
,
Karim A.
Elmestekawy
,
Pietro
Caprioglio
,
Igal
Levine
,
Alexandra A.
Sheader
,
Esther Y.-H.
Hung
,
Fengning
Yang
,
Daniel T. W.
Toolan
,
Rachel C.
Kilbride
,
Karl-Augustin
Zaininger
,
James M.
Ball
,
M. Greyson
Christoforo
,
Nakita K.
Noel
,
Laura M.
Herz
,
Dominik J.
Kubicki
,
Henry J.
Snaith
Diamond Proposal Number(s):
[33462]
Open Access
Abstract: Perovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which we use as highly effective precursor phases for subsequent transformation to α-formamidinium lead triiodide (α-FAPbI3), fully processed under ambient conditions. PSCs utilising our α-FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and “damp heat” (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the α-phase.
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Nov 2024
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