Imperial College London

ProfessorAronWalsh

Faculty of EngineeringDepartment of Materials

Chair in Materials Design
 
 
 
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Contact

 

+44 (0)20 7594 1178a.walsh Website

 
 
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Location

 

2.10Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

559 results found

Morita K, Golomb MJ, Rivera M, Walsh Aet al., 2023, Models of Polaron Transport in Inorganic and Hybrid Organic-Inorganic Titanium Oxides, CHEMISTRY OF MATERIALS, Vol: 35, Pages: 3652-3659, ISSN: 0897-4756

Journal article

Tolborg K, Walsh A, 2023, Exploring the High-Temperature Stabilization of Cubic Zirconia from Anharmonic Lattice Dynamics, CRYSTAL GROWTH & DESIGN, Vol: 23, Pages: 3314-3319, ISSN: 1528-7483

Journal article

Golomb MJ, Tolborg K, Calbo J, Walsh Aet al., 2023, Role of Counterions in the Structural Stabilisation of Redox-Active Metal-Organic Frameworks, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 29, ISSN: 0947-6539

Journal article

Mosquera-Lois I, Kavanagh SR, Walsh A, Scanlon DOet al., 2023, Identifying the ground state structures of point defects in solids, NPJ COMPUTATIONAL MATERIALS, Vol: 9

Journal article

Twyman NM, Walsh A, Buonassisi T, 2023, Reply to Comment on "Environmental Stability of Crystals: A Greedy Screening", CHEMISTRY OF MATERIALS, Vol: 35, Pages: 804-804, ISSN: 0897-4756

Journal article

Zhang H, Debroye E, Vina-Bausa B, Valli D, Fu S, Zheng W, Di Virgilio L, Gao L, Frost JM, Walsh A, Hofkens J, Wang H, Bonn Met al., 2023, Stable Mott Polaron State Limits the Charge Density in Lead Halide Perovskites, ACS ENERGY LETTERS, Vol: 8, Pages: 420-428, ISSN: 2380-8195

Journal article

Woo YW, Li Z, Jung Y-K, Park J-S, Walsh Aet al., 2023, Inhomogeneous Defect Distribution in Mixed- Polytype Metal Halide Perovskites, ACS ENERGY LETTERS, Vol: 8, Pages: 356-360, ISSN: 2380-8195

Journal article

Shin SJ, Gittins JW, Balhatchet CJ, Walsh A, Forse ACet al., 2023, Metal–Organic Framework Supercapacitors: Challenges and Opportunities, Advanced Functional Materials, ISSN: 1616-301X

Supercapacitors offer superior energy storage capabilities than traditional capacitors, making them useful for applications such as electric vehicles and rapid large-scale energy storage. The energy storage performance of these devices relies on electrical double-layer capacitance and/or pseudocapacitance from rapid reversible redox reactions. Metal–organic frameworks (MOFs) have recently emerged as a new class of electrode materials with promising supercapacitor performances and capacitances that exceed those of traditional materials. However, the comparison of the supercapacitor performance of a porous carbon and a state-of-the-art MOF highlights a number of challenges for MOF supercapacitors, including low potential windows, limited cycle lifetimes, and poor rate performances. It is proposed that the well-defined and tuneable chemical structures of MOFs present a number of avenues for improving supercapacitor performance. Recent experimental and theoretical work on charging mechanisms in MOF-based supercapacitors is also discussed, and it is found that there is a need for more studies that elucidate the charge storage and degradation mechanisms. Ultimately, a deeper understanding will lead to design principles for realizing improved supercapacitor energy storage devices.

Journal article

Steele JA, Braeckevelt T, Prakasam V, Degutis G, Yuan H, Jin H, Solano E, Puech P, Basak S, Pintor-Monroy MI, Van Gorp H, Fleury G, Yang RX, Lin Z, Huang H, Debroye E, Chernyshov D, Chen B, Wei M, Hou Y, Gehlhaar R, Genoe J, De Feyter S, Rogge SMJ, Walsh A, Sargent EH, Yang P, Hofkens J, Van Speybroeck V, Roeffaers MBJet al., 2022, An embedded interfacial network stabilizes inorganic CsPbI3 perovskite thin films, NATURE COMMUNICATIONS, Vol: 13

Journal article

Mosquera-Lois I, Kavanagh SR, Walsh A, Scanlon DOet al., 2022, ShakeNBreak: Navigating the defect configurationallandscape, Journal of Open Source Software, Vol: 7, Pages: 4817-4817

Journal article

Kavanagh SR, Savory CN, Liga SM, Konstantatos G, Walsh A, Scanlon DOet al., 2022, Frenkel Excitons in Vacancy-Ordered Titanium Halide Perovskites (Cs<sub>2</sub>TiX<sub>6</sub>), JOURNAL OF PHYSICAL CHEMISTRY LETTERS, ISSN: 1948-7185

Journal article

Simenas M, Balciunas S, Gagor A, Pieniazek A, Tolborg K, Kinka M, Klimavicius V, Svirskas S, Kalendra V, Ptak M, Szewczyk D, Herman AP, Kudrawiec R, Sieradzki A, Grigalaitis R, Walsh A, Maczka M, Banys Jet al., 2022, Mixology of MA1-XEAXPbI3 Hybrid Perovskites: Phase Transitions, Cation Dynamics, and Photoluminescence, CHEMISTRY OF MATERIALS, Vol: 34, Pages: 10104-10112, ISSN: 0897-4756

Journal article

Agbenyeke R, Andreasen JW, Benhaddou N, Bowers JW, Breternitz J, Bar M, Dimitrievska M, Fermin DJ, Ganose A, Hawkins C, Jaramillo R, Kavanagh SR, Kondrotas R, Major JD, Mandati S, Nicolson A, Bjorkman CP, Savory C, Scanlon DO, Schorr S, Scragg JJS, Sheppard A, Shin B, Siebentritt S, Sood M, Sopiha K, Spalatu N, Tang J, Walsh A, Weiss TP, Woods-Robinson R, Yetkin HAet al., 2022, Materials design and bonding: general discussion, FARADAY DISCUSSIONS, Vol: 239, Pages: 375-404, ISSN: 1359-6640

Journal article

Andreasen JW, Breternitz J, Baer M, Dale PJ, Dimitrievska M, Fermin DJ, Fleck N, Hages CJ, Havryliuk Y, Hawkins C, Jaramillo R, Kavanagh SR, Kayastha P, Kondrotas R, Lapalikar V, Mandati S, Mitzi DB, Bjoerkman CP, Savory C, Scragg JJS, Shin B, Siebentritt S, Sood M, Tiwari D, Valdes M, Walsh A, Weiss TP, Woo YW, Woods-Robinson R, Yetkin HAet al., 2022, Bulk and surface characterisation techniques of solar absorbers: general discussion, FARADAY DISCUSSIONS, Vol: 239, Pages: 180-201, ISSN: 1359-6640

Journal article

Andreasen JW, Arca E, Bowers JW, Bar M, Breternitz J, Dale PJ, Dimitrievska M, Fermin DJ, Ganose A, Hages CJ, Hobson T, Jaramillo R, Kavanagh SR, Kayastha P, Kondrotas R, Lee J, Major JD, Mandati S, Mitzi DB, Scanlon DO, Schorr S, Scragg JJS, Shin B, Siebentritt S, Smiles M, Sood M, Sopiha K, Spalatu N, Sutton M, Unold T, Valdes M, Walsh A, Wang M, Wang X, Weiss TP, Woo YW, Woods-Robinson R, Tiwari Det al., 2022, Novel chalcogenides, pnictides and defect-tolerant semiconductors: general discussion, FARADAY DISCUSSIONS, Vol: 239, Pages: 287-316, ISSN: 1359-6640

Journal article

Walsh A, 2022, Concluding remarks: emerging inorganic materials in thin-film photovoltaics, FARADAY DISCUSSIONS, Vol: 239, Pages: 405-412, ISSN: 1359-6640

Journal article

Kavanagh SR, Scanlon DO, Walsh A, Freysoldt Cet al., 2022, Impact of metastable defect structures on carrier recombination in solar cells, FARADAY DISCUSSIONS, Vol: 239, Pages: 339-356, ISSN: 1359-6640

Journal article

Tolborg K, Klarbring J, Ganose AM, Walsh Aet al., 2022, Free energy predictions for crystal stability and synthesisability, Digital Discovery, Vol: 1, Pages: 586-595

What is the likelihood that a hypothetical material—the combination of a composition and crystal structure—can be formed? Underpinning the reliability of predictions for local or global crystal stability is the choice of thermodynamic potential. Here, we discuss recent advances in free energy descriptions for crystals including both harmonic and anharmonic phonon contributions to the vibrational entropy. We critically discuss some of the techniques and descriptors, including data-driven machine learning approaches, being developed to assess the stability and synthesisability of solids. Avenues are highlighted that deserve further attention including thermodynamic and kinetic factors that govern the accessibility of metastable structures away from equilibrium.

Journal article

Jung Y-K, Abdulla M, Friend RH, Stranks SD, Walsh Aet al., 2022, Pressure-induced non-radiative losses in halide perovskite light-emitting diodes, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 10, Pages: 12560-12568, ISSN: 2050-7526

Journal article

Wang X, Ganose AM, Kavanagh SR, Walsh Aet al., 2022, Band versus Polaron: Charge Transport in Antimony Chalcogenides, ACS ENERGY LETTERS, Vol: 7, Pages: 2954-2960, ISSN: 2380-8195

Journal article

Huang Y-T, Kavanagh S, Righetto M, Rusu M, Levine I, Unold T, Zelewiski S, Sneyd A, Zhang K, Dai L, Britton A, Ye J, Julin J, Napari M, Zhang Z, Xiao J, Laitinen M, Torrente-Murciano L, Stranks S, Rao A, Herz L, Scanlon D, Walsh A, Hoye Ret al., 2022, Strong absorption and ultrafast localisation in NaBiS2 nanocrystals with slow charge-carrier recombination, Nature Communications, Vol: 13, ISSN: 2041-1723

I-V-VI2 ternary chalcogenides are gaining attention as earth-abundant, nontoxic, and air-stable absorbers for photovoltaic applications. However, the semiconductors explored thus far have slow absorption onsets, and their charge-carrier transport is not well understood yet. Herein, we investigate cation-disordered NaBiS2 nanocrystals, which have a steep absorption onset, with absorption coefficients reaching >105 cm-1 just above its pseudo-direct bandgap of 1.4 eV. Surprisingly, we also observe an ultrafast (at picosecond-time scale) photoconductivity decay and long-lived charge-carrier population persisting for over one microsecond in NaBiS2 nanocrystals. These unusual features arise because of the localised, non-bonding S p character of the upper valence band, which leads to a high density of electronic states at the band edges, ultrafast localisation of spatially-separated electrons and holes, as well as the slow decay of trapped holes. This work reveals the critical role of cation disorder in these systems on both absorption characteristics and charge-carrier kinetics.

Journal article

Ganose A, Scanlon D, Walsh A, Hoye Ret al., 2022, The defect challenge of wide-bandgap semiconductors for photovoltaics and beyond, Nature Communications, Vol: 13, ISSN: 2041-1723

The optoelectronic performance of wide-bandgap semiconductors often cannot compete with that of their defect-tolerant small-bandgap counterpart. Here, the authors outline three main challenges to overcome for mitigating the impact of defects in wide-bandgap semiconductors.

Journal article

Squires AG, Davies DW, Kim S, Scanlon DO, Walsh A, Morgan BJet al., 2022, Low electronic conductivity of Li7La3Zr2O12 solid electrolytes from first principles, Physical Review Materials, Vol: 6, Pages: 1-12, ISSN: 2475-9953

Lithium-rich garnets such as Li7La3Zr2O12 (LLZO) are promising solid electrolytes with potential application in all-solid-state batteries that use lithium-metal anodes. The practical use of garnet electrolytes is limited by pervasive lithium-dendrite growth, which leads to short-circuiting and cell failure. One proposed mechanism of lithium-dendrite growth is the direct reduction of lithium ions to lithium metal within the electrolyte, and lithium garnets have been suggested to be particularly susceptible to this dendrite-growth mechanism due to high electronic conductivities relative to other solid electrolytes. The electronic conductivities of LLZO and other lithium-garnet solid electrolytes, however, are not yet well characterized. Here, we present a general scheme for calculating the intrinsic electronic conductivity of a nominally insulating material under variable synthesis conditions from first principles, and apply this to the prototypical lithium-garnet LLZO. Our model predicts that under typical battery operating conditions, electron and hole mobilities are low (<1cm2V−1s−1), and bulk electron and hole carrier concentrations are negligible, irrespective of initial synthesis conditions or dopant levels. These results suggest that the bulk electronic conductivity of LLZO is not sufficiently high to cause bulk lithium-dendrite growth during cell operation, and that any non-negligible electronic conductivity in lithium garnet samples is likely due to extended defects or surface contributions.1

Journal article

Wang S, Huang M, Wu Y-N, Chu W, Zhao J, Walsh A, Gong X-G, Wei S-H, Chen Set al., 2022, Effective lifetime of non-equilibrium carriers in semiconductors from non-adiabatic molecular dynamics simulations, NATURE COMPUTATIONAL SCIENCE, Vol: 2, Pages: 486-+

Journal article

Moriarty A, Morita K, Butler KT, Walsh Aet al., 2022, UnlockNN: Uncertainty quantification for neural networkmodels of chemical systems, Journal of Open Source Software, Vol: 7, Pages: 3700-3700

Journal article

Morita K, Kumagai Y, Oba F, Walsh Aet al., 2022, Switchable Electric Dipole from Polaron Localization in Dielectric Crystals, PHYSICAL REVIEW LETTERS, Vol: 129, ISSN: 0031-9007

Journal article

Pastor E, Sachs M, Selim S, Durrant JR, Bakulin AA, Walsh Aet al., 2022, Electronic defects in metal oxide photocatalysts, NATURE REVIEWS MATERIALS, Vol: 7, Pages: 503-521, ISSN: 2058-8437

Journal article

Liu T, Zhang X, Guan J, Catlow CRA, Walsh A, Sokol AA, Buckeridge Jet al., 2022, Insight into the Fergusonite-Scheelite Phase Transition of ABO<sub>4</sub>-Type Oxides by Density Functional Theory: A Case Study of the Subtleties of the Ground State of BiVO<sub>4</sub>, CHEMISTRY OF MATERIALS, Vol: 34, Pages: 5334-5343, ISSN: 0897-4756

Journal article

Huang J, Golomb MJ, Kavanagh SR, Tolborg K, Ganose AM, Walsh Aet al., 2022, Band gap opening from displacive instabilities in layered covalent-organic frameworks, Journal of Materials Chemistry A, Vol: 10, Pages: 13500-13507, ISSN: 2050-7488

Covalent organic frameworks (COFs) offer a high degree of chemical and structural flexibility. There is a large family of COFs built from 2D sheets that are stacked to form extended crystals. While it has been common to represent the stacking as eclipsed with one repeating layer (“AA”), there is growing evidence that a more diverse range of stacking sequences is accessible. Herein, we report a computational study using density functional theory of layer stacking in two prototypical COFs, Tp-Azo and DAAQ-TFP, which have shown high performance as Li-ion battery electrodes. We find a striking preference for slipped structures with horizontal offsets between layers ranging from 1.7 Å to 3.5 Å in a potential energy minimum that forms a low energy ring. The associated symmetry breaking results in a pronounced change in the underlying electronic structure. A band gap opening of 0.8–1.4 eV is found due to modifications of the underlying valence and conduction band dispersion as explained from changes in the π orbital overlap. The implications for the screening and selection of COF for energy applications are discussed.

Journal article

Ma S, Jung Y-K, Ahn J, Kyhm J, Tan J, Lee H, Jang G, Lee CU, Walsh A, Moon Jet al., 2022, Elucidating the origin of chiroptical activity in chiral 2D perovskites through nano-confined growth, NATURE COMMUNICATIONS, Vol: 13

Journal article

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