Professor Buddhika Mendis' Outputs (81)

On the principle of reciprocity in inelastic electron scattering (2024)
Journal Article
Mendis, B. G. (2024). On the principle of reciprocity in inelastic electron scattering. Acta Crystallographica Section A: Foundations and Advances, 80(6), 457-459. https://doi.org/10.1107/s2053273324009550

In electron microscopy the principle of reciprocity is often used to imply time reversal symmetry. While this is true for elastic scattering, its applicability to inelastic scattering is less well established. From the second law of thermodynamics, t... Read More about On the principle of reciprocity in inelastic electron scattering.

La₂O₂MQ₂ phases: stability and synthetic challenges (2024)
Journal Article
Hebberd, G. R., Mendis, B., Bowen, L., Clark, S. J., & Mccabe, E. E. (2024). La₂O₂MQ₂ phases: stability and synthetic challenges. Solid State Sciences, 157, Article 107719. https://doi.org/10.1016/j.solidstatesciences.2024.107719

Oxychalcogenides containing transition metal or p block cations have potential for thermoelectric, photocatalytic and magnetic applications but the synthetic pathways to these quaternary phases are not fully understood. This presents a challenge to t... Read More about La₂O₂MQ₂ phases: stability and synthetic challenges.

Se Inter-Diffusion Limits Absorber Layer Grain Growth in CdSe - CdTe Photovoltaics (2024)
Journal Article
Altamimi, T. F. S., Leaver, J. F., Durose, K., Major, J. D., & Mendis, B. G. (2024). Se Inter-Diffusion Limits Absorber Layer Grain Growth in CdSe - CdTe Photovoltaics. PRX Energy, 3(2), Article 023002. https://doi.org/10.1103/prxenergy.3.023002

Diffusion of Se from the CdSe window layer into the CdTe absorber improves the short circuit current density by narrowing the band gap and increasing the carrier lifetime. Thicker CdSe layers, however, show a dramatic loss in photocurrent collection... Read More about Se Inter-Diffusion Limits Absorber Layer Grain Growth in CdSe - CdTe Photovoltaics.

Grain-Boundary Structural Relaxation in Sb2Se3 Thin-Film Photovoltaics (2024)
Journal Article
Lomas-Zapata, R., McKenna, K., Ramasse, Q., Williams, R., Phillips, L., Durose, K., Major, J., & Mendis, B. (2024). Grain-Boundary Structural Relaxation in Sb2Se3 Thin-Film Photovoltaics. PRX Energy, 3(1), Article 013006. https://doi.org/10.1103/prxenergy.3.013006

Grain boundaries play an important role in the efficiency of thin-film photovoltaics, where the absorber layer is invariably polycrystalline. Density-functional-theory simulations have previously identified a “self-healing” mechanism in Sb2Se3 that p... Read More about Grain-Boundary Structural Relaxation in Sb2Se3 Thin-Film Photovoltaics.

Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering (2024)
Journal Article
Mendis, B. (2024). Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering. Acta Crystallographica Section A: Foundations and Advances, 80(2), 178-188. https://doi.org/10.1107/s2053273323010690

The strong interaction of high‐energy electrons with a crystal results in both dynamical elastic scattering and inelastic events, particularly phonon and plasmon excitation, which have relatively large cross sections. For accurate crystal structure r... Read More about Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering.

Modelling dynamical 3D electron diffraction intensities. I. A scattering cluster algorithm (2024)
Journal Article
Mendis, B. (2024). Modelling dynamical 3D electron diffraction intensities. I. A scattering cluster algorithm. Acta Crystallographica Section A: Foundations and Advances, 80(2), 167-177. https://doi.org/10.1107/s2053273323010689

Three‐dimensional electron diffraction (3D‐ED) is a powerful technique for crystallographic characterization of nanometre‐sized crystals that are too small for X‐ray diffraction. For accurate crystal structure refinement, however, it is important tha... Read More about Modelling dynamical 3D electron diffraction intensities. I. A scattering cluster algorithm.

A simulation study of the role of anisotropic charge transport and grain boundary recombination in thin-film Sb2Se3 photovoltaics (2023)
Journal Article
Lomas-Zapata, R., Prior, A., & Mendis, B. (2023). A simulation study of the role of anisotropic charge transport and grain boundary recombination in thin-film Sb2Se3 photovoltaics. Solar Energy, 264, Article 112054. https://doi.org/10.1016/j.solener.2023.112054

The crystal structure of Sb2Se3, which consists of [0 0 1] oriented ribbons held together by weak van der Waals forces, gives rise to unique absorber layer properties different from other more conventional photovoltaic materials, such as Si or CdTe.... Read More about A simulation study of the role of anisotropic charge transport and grain boundary recombination in thin-film Sb2Se3 photovoltaics.

Quantifying Molecular Disorder in Tri-Isopropyl Silane (TIPS) Pentacene Using Variable Coherence Transmission Electron Microscopy (2023)
Journal Article
Alanazi, F., Eggeman, A. S., Stavrou, K., Danos, A., Monkman, A. P., & Mendis, B. G. (2023). Quantifying Molecular Disorder in Tri-Isopropyl Silane (TIPS) Pentacene Using Variable Coherence Transmission Electron Microscopy. Journal of Physical Chemistry Letters, 14(36), 8183-8190. https://doi.org/10.1021/acs.jpclett.3c01344

Structural disorder in molecular crystals is a fundamental limitation for achieving high charge carrier mobilities. Quantifying and uncovering the mechanistic origins of disorder are, however, extremely challenging. Here we use variable coherence tra... Read More about Quantifying Molecular Disorder in Tri-Isopropyl Silane (TIPS) Pentacene Using Variable Coherence Transmission Electron Microscopy.

Twist-induced interlayer charge buildup in a WS2 bilayer revealed by electron Compton scattering and density functional theory (2023)
Journal Article
Talmantaite, A., Xie, Y., Cohen, A., Mohapatra, P., Ismach, A., Mizoguchi, T., Clark, S., & Mendis, B. (2023). Twist-induced interlayer charge buildup in a WS2 bilayer revealed by electron Compton scattering and density functional theory. Physical Review B, 107(23), Article 235424. https://doi.org/10.1103/physrevb.107.235424

Exotic properties emerge from the electronic structure of few-layer transition-metal dichalcogenides (TMDs), such as direct band gaps in monolayers and moiré excitons in twisted bilayers, which are exploited in modern optoelectronic devices and twist... Read More about Twist-induced interlayer charge buildup in a WS2 bilayer revealed by electron Compton scattering and density functional theory.

A “Phase Scrambling” Algorithm for Parallel Multislice Simulation of Multiple Phonon and Plasmon Scattering Configurations (2023)
Journal Article
Mendis, B. G. (2023). A “Phase Scrambling” Algorithm for Parallel Multislice Simulation of Multiple Phonon and Plasmon Scattering Configurations. Microscopy and Microanalysis, 29(3), 1111-1123. https://doi.org/10.1093/micmic/ozad052

Multislice simulations of 4D scanning transmission electron microscopy (4D STEM) data are computationally demanding due to the large number of STEM probe positions that must be calculated. For accurate analysis, inelastic scattering from phonons and... Read More about A “Phase Scrambling” Algorithm for Parallel Multislice Simulation of Multiple Phonon and Plasmon Scattering Configurations.

Coherent electron Compton scattering and the non-diagonal electron momentum density of solids (2022)
Journal Article
Mendis, B. (2023). Coherent electron Compton scattering and the non-diagonal electron momentum density of solids. Ultramicroscopy, 245, https://doi.org/10.1016/j.ultramic.2022.113664

Experimental techniques that probe the electronic structure of crystalline solids are vital for exploring novel condensed matter phenomena. In coherent Compton scattering the Compton signal due to interference of an incident and Bragg diffracted beam... Read More about Coherent electron Compton scattering and the non-diagonal electron momentum density of solids.

Towards Electron Energy Loss Compton Spectra Free From Dynamical Diffraction Artifacts (2022)
Journal Article
Mendis, B. G., & Talmantaite, A. (2022). Towards Electron Energy Loss Compton Spectra Free From Dynamical Diffraction Artifacts. Microscopy and Microanalysis, 28(6), 1971–1980. https://doi.org/10.1017/s1431927622012223

The Compton signal in electron energy loss spectroscopy (EELS) is used to determine the projected electron momentum density of states for the solid. A frequent limitation however is the strong dynamical scattering of the incident electron beam within... Read More about Towards Electron Energy Loss Compton Spectra Free From Dynamical Diffraction Artifacts.

Structure and electronic properties of domain walls and stacking fault defects in prospective photoferroic materials bournonite and enargite (2022)
Journal Article
Rigby, O., Richards-Hlabangana, T., Ramasse, Q., MacLaren, I., Lomas-Zapata, R., Rumsey, M., McKenna, K., & Mendis, B. (2022). Structure and electronic properties of domain walls and stacking fault defects in prospective photoferroic materials bournonite and enargite. Journal of Applied Physics, 132(18), Article 185001. https://doi.org/10.1063/5.0095091

Bournonite (CuPbSbS3) and enargite (Cu3AsS4) have recently been used as absorber layers in thin-film photovoltaic devices due to their ideal bandgap and ferroelectric properties. An understanding of the ferroelectric domain structure in these materia... Read More about Structure and electronic properties of domain walls and stacking fault defects in prospective photoferroic materials bournonite and enargite.

Background subtraction in electron Compton spectroscopy (2022)
Journal Article
Mendis, B. (2022). Background subtraction in electron Compton spectroscopy. Micron, 163, Article 103363. https://doi.org/10.1016/j.micron.2022.103363

Compton scattering in electron energy loss spectroscopy (EELS) is used to quantify the momentum distribution of occupied electronic states in a solid. The Compton signal is a broad feature with a width of several hundred eV. Furthermore, the weak int... Read More about Background subtraction in electron Compton spectroscopy.

Quantum theory of magnon excitation by high energy electron beams (2022)
Journal Article
Mendis, B. (2022). Quantum theory of magnon excitation by high energy electron beams. Ultramicroscopy, 239, Article 113548. https://doi.org/10.1016/j.ultramic.2022.113548

The role of magnon inelastic scattering in high energy electron diffraction of spin unpolarised electron beams, including vortex beams, is investigated theoretically for a Heisenberg ferromagnet. The interaction is between the atomic magnetic dipoles... Read More about Quantum theory of magnon excitation by high energy electron beams.

Selenium passivates grain boundaries in alloyed CdTe solar cells (2022)
Journal Article
Fiducia, T., Howkins, A., Abbas, A., Mendis, B., Munshi, A., Barth, K., Sampath, W., & Walls, J. (2022). Selenium passivates grain boundaries in alloyed CdTe solar cells. Solar Energy Materials and Solar Cells, 238, Article 111595. https://doi.org/10.1016/j.solmat.2022.111595

Cadmium telluride (CdTe) solar cells have achieved efficiencies of over 22%, despite having absorber layer grain sizes less than 10 μm and hence a very high density of grain boundaries. Recent research has shown that this is possible because of parti... Read More about Selenium passivates grain boundaries in alloyed CdTe solar cells.

Differing Impacts of Blended Fullerene Acceptors on the Performance of Ternary Organic Solar Cells (2021)
Journal Article
Palacios-Gómez, D. A., Huerta Flores, A. M., MacKenzie, R. C., Pearson, C., Alanazi, F., Mendis, B. G., & Groves, C. (2021). Differing Impacts of Blended Fullerene Acceptors on the Performance of Ternary Organic Solar Cells. ACS Applied Energy Materials, 4(10), 10867-10876. https://doi.org/10.1021/acsaem.1c01833

Organic photovoltaic (OPV) devices offer the ability to tune the electronic and optical properties of the active layer by selection of a wide range of molecules; however, their power conversion efficiencies currently lag other competing photovoltaic... Read More about Differing Impacts of Blended Fullerene Acceptors on the Performance of Ternary Organic Solar Cells.

A semi-classical theory of magnetic inelastic scattering in transmission electron energy loss spectroscopy (2021)
Journal Article
Mendis, B. (2021). A semi-classical theory of magnetic inelastic scattering in transmission electron energy loss spectroscopy. Ultramicroscopy, 230, Article 113390. https://doi.org/10.1016/j.ultramic.2021.113390

The feasibility of detecting magnetic excitations using monochromated electron energy loss spectroscopy in the transmission electron microscope is examined. Inelastic scattering cross-sections are derived using a semi-classical electrodynamic model,... Read More about A semi-classical theory of magnetic inelastic scattering in transmission electron energy loss spectroscopy.

Surface Core Hole Electron Energy-Loss Fine Structure in MgO: Experiment and Theory (2021)
Journal Article
Mendis, B. (2021). Surface Core Hole Electron Energy-Loss Fine Structure in MgO: Experiment and Theory. Microscopy and Microanalysis, 27(6), 1316-1327. https://doi.org/10.1017/s1431927621012691

Core holes are an important contributing factor to the core-loss fine structure in electron energy-loss spectroscopy (EELS). While there has been much work on bulk materials, less is known about core hole screening in more complex dielectric environm... Read More about Surface Core Hole Electron Energy-Loss Fine Structure in MgO: Experiment and Theory.

Removal of core hole distortion from ionization edges in electron energy loss spectroscopy (2021)
Journal Article
Mendis, B., & Ramasse, Q. (2021). Removal of core hole distortion from ionization edges in electron energy loss spectroscopy. Physical Review B, 103(20), Article 205102. https://doi.org/10.1103/physrevb.103.205102

The near-edge fine structure in electron energy loss spectra is used to probe the electronic bonding environment of materials at high spatial resolution. Often, however, deviations from the ground state electronic properties are observed, due to the... Read More about Removal of core hole distortion from ionization edges in electron energy loss spectroscopy.