SwePub - search: WFRF:(Giangrisostomi Erika)

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1.	Ali, Azmat, et al. (author) The Electronic Impact of Light-Induced Degradation in CsPbBr3 Perovskite Nanocrystals at Gold Interfaces 2024 In: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 15:14, s. 3721-3727 Journal article (peer-reviewed)abstract The understanding of the interfacial properties in perovskite devices under irradiation is crucial for their engineering. In this study we show how the electronic structure of the interface between CsPbBr3 perovskite nanocrystals (PNCs) and Au is affected by irradiation of X-rays, near-infrared (NIR), and ultraviolet (UV) light. The effects of X-ray and light exposure could be differentiated by employing low-dose X-ray photoelectron spectroscopy (XPS). Apart from the common degradation product of metallic lead (Pb0), a new intermediate component (Pbint) was identified in the Pb 4f XPS spectra after exposure to high intensity X-rays or UV light. The Pbint component is determined to be monolayer metallic Pb on-top of the Au substrate from underpotential deposition (UPD) of Pb induced from the breaking of the perovskite structure allowing for migration of Pb2+.
2.	Andersson, Edvin K. W., et al. (author) Initial SEI formation in LiBOB-, LiDFOB- and LiBF4-containing PEO electrolytes 2024 In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 12:15, s. 9184-9199 Journal article (peer-reviewed)abstract A limiting factor for solid polymer electrolyte (SPE)-based Li-batteries is the functionality of the electrolyte decomposition layer that is spontaneously formed at the Li metal anode. A deeper understanding of this layer will facilitate its improvement. This study investigates three SPEs – polyethylene oxide:lithium tetrafluoroborate (PEO:LiBF4), polyethylene oxide:lithium bis(oxalate)borate (PEO:LiBOB), and polyethylene oxide:lithium difluoro(oxalato)borate (PEO:LiDFOB) – using a combination of electrochemical impedance spectroscopy (EIS), galvanostatic cycling, in situ Li deposition photoelectron spectroscopy (PES), and ab initio molecular dynamics (AIMD) simulations. Through this combination, the cell performance of PEO:LiDFOB can be connected to the initial SPE decomposition at the anode interface. It is found that PEO:LiDFOB had the highest capacity retention, which is correlated to having the least decomposition at the interface. This indicates that the lower SPE decomposition at the interface still creates a more effective decomposition layer, which is capable of preventing further electrolyte decomposition. Moreover, the PES results indicate formation of polyethylene in the SEI in cells based on PEO electrolytes. This is supported by AIMD that shows a polyethylene formation pathway through free-radical polymerization of ethylene.
3.	Cappel, Ute B., et al. (author) Electronic Structure Characterization of Cross-Linked Sulfur Polymers 2018 In: ChemPhysChem. - : WILEY-V C H VERLAG GMBH. - 1439-4235 .- 1439-7641. ; 19:9, s. 1041-1047 Journal article (peer-reviewed)abstract Cross-linked polymers of elemental sulfur are of potential interest for electronic applications as they enable facile thin-film processing of an abundant and inexpensive starting material. Here, we characterize the electronic structure of a cross-linked sulfur/diisopropenyl benzene (DIB) polymer by a combination of soft and hard X-ray photoelectron spectroscopy (SOXPES and HAXPES). Two different approaches for enhancing the conductivity of the polymer are compared: the addition of selenium in the polymer synthesis and the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) during film preparation. For the former, we observe the incorporation of Se into the polymer structure resulting in a changed valence-band structure. For the latter, a Fermi level shift in agreement with p-type doping of the polymer is observed and also the formation of a surface layer consisting mostly of TFSI anions.
4.	Cappel, Ute B, et al. (author) Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells. 2017 In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:40, s. 34970-34978 Journal article (peer-reviewed)abstract ) with the element specificity and chemical sensitivity of core-level photoelectron spectroscopy. By carrying out measurements at a synchrotron beamline optimized for low X-ray fluxes, we are able to avoid sample changes due to X-ray illumination and are therefore able to monitor what sample changes are induced by visible illumination only. We find that laser illumination causes partially reversible chemistry in the surface region, including enrichment of bromide at the surface, which could be related to a phase separation into bromide- and iodide-rich phases. We also observe a partially reversible formation of metallic lead in the perovskite structure. These processes occur on the time scale of minutes during illumination. The presented methodology has a large potential for understanding light-induced chemistry in photoactive materials and could specifically be extended to systematically study the impact of morphology and composition on the photostability of metal halide perovskites.
5.	Giangrisostomi, Erika, et al. (author) Inhomogeneity of Cleaved Bulk MoS2 and Compensation of Its Charge Imbalances by Room-Temperature Hydrogen Treatment 2023 In: Advanced Materials Interfaces. - : Wiley. - 2196-7350. Journal article (peer-reviewed)abstract Synthetic single crystals of bulk molybdenum disulphide cleaved in ultrahigh vacuum are mapped across a large (approximate to 25 mm(2)) area by X-ray photoelectron spectroscopy, both statically and transiently following above-bandgap excitation by an ultrafast laser. This work finds that: I) A cleaved surface typically displays spatially inhomogeneous properties, manifested by large (approximate to 1 eV) variations in binding energy and band bending and variable degrees of stability of those over time as a result of variable gas uptakes from the residual atmosphere. II) Moderate (350 degrees C) annealing and exposure to molecular hydrogen can be cycled to switch between smaller and larger surface band bending, the switch being reversible but strongly sample-position dependent. III) Upon exposure to atomic hydrogen, the binding energy of the entire surface levels out to a common (within <0.05 eV) value corresponding to a Fermi level pinned close to mid-bandgap. Such remarkable effect is attributed to the ability of hydrogen atoms to serve as donors and acceptors alike, thus neutralizing local charge imbalances inevitably present at the surface in consequence of intrinsic and/or cleavage-induced defects. With subsequent moderate annealing, the hydrogenated surface preserves a fairly homogenous electronic state which is however characterized by a lower binding energy and little to no band bending.
6.	Giangrisostomi, Erika, et al. (author) Low Dose Photoelectron Spectroscopy at BESSY II : Electronic structure of matter in its native state 2018 In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 224:SI, s. 68-78 Journal article (peer-reviewed)abstract The implementation of a high-transmission, angular-resolved time-of-Right electron spectrometer with a 1.25 MHz pulse selector at the PM4 soft X-ray dipole beamline of the synchrotron BESSY II creates unique capabilities to inquire electronic structure via photoelectron spectroscopy with a minimum of radiation dose. Solid-state samples can be prepared and characterized with standard UHV techniques and rapidly transferred from various preparation chambers to a 4-axis temperature-controlled measurement stage. A synchronized MHz laser system enables excited-state characterization and dynamical studies starting from the picosecond timescale. This article introduces the principal characteristics of the PM4 beamline and LowDosePES end-station. Recent results from graphene, an organic hole transport material for solar cells and the transition metal dichalcogenide MoS2 are presented to demonstrate the instrument performances. (C) 2017 The Authors. Published by Elsevier B.V.
7.	Kuehn, Danilo, et al. (author) Directional sub-femtosecond charge transfer dynamics and the dimensionality of 1T-TaS2 2019 In: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9 Journal article (peer-reviewed)abstract For the layered transition metal dichalcogenide 1T-TaS2, we establish through a unique experimental approach and density functional theory, how ultrafast charge transfer in 1T-TaS2 takes on isotropic three-dimensional character or anisotropic two-dimensional character, depending on the commensurability of the charge density wave phases of 1T-TaS2. The X-ray spectroscopic core-hole-clock method prepares selectively in-and out-of-plane polarized sulfur 3p orbital occupation with respect to the 1T-TaS2 planes and monitors sub-femtosecond wave packet delocalization. Despite being a prototypical two-dimensional material, isotropic three-dimensional charge transfer is found in the commensurate charge density wave phase (CCDW), indicating strong coupling between layers. In contrast, anisotropic two-dimensional charge transfer occurs for the nearly commensurate phase (NCDW). In direct comparison, theory shows that interlayer interaction in the CCDW phase - not layer stacking variations - causes isotropic three-dimensional charge transfer. This is presumably a general mechanism for phase transitions and tailored properties of dichalcogenides with charge density waves.
8.	Kühn, Danilo, et al. (author) Capabilities of Angle Resolved Time of Flight electron spectroscopy with the 60 degrees wide angle acceptance lens 2018 In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 224, s. 45-50 Journal article (peer-reviewed)abstract The simultaneous detection of energy, momentum and temporal information in electron spectroscopy is the key aspect to enhance the detection efficiency in order to broaden the range of scientific applications. Employing a novel 60 degrees wide angle acceptance lens system, based on an additional accelerating electron optical element, leads to a significant enhancement in transmission over the previously employed 30 degrees electron lenses. Due to the performance gain, optimized capabilities for time resolved electron spectroscopy and other high transmission applications with pulsed ionizing radiation have been obtained. The energy resolution and transmission have been determined experimentally utilizing BESSY II as a photon source. Four different and complementary lens modes have been characterized. (C) 2017 The Authors. Published by Elsevier B.V.
9.	Lanzilotto, Valeria, et al. (author) Spectroscopic Fingerprints of Carbon Nitride Functional Groups Locked-up in Intermolecular H-bonding Interactions In: Chemistry: A European Journal. - 0947-6539 .- 1521-3765. Journal article (peer-reviewed)abstract We have investigated the effect of intermolecular H- bonding interactions on the local electronic structure of N- functionalities, amino group and pyridine-like N, which are characteristic of a new class of metal-free polymeric photo-catalysts named graphitic carbon nitrides, g-C3N4. Specifically, we have performed a characterization of the melamine molecule, a building block of g-C3N4, combining X-ray photoemission (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecule has been studied in the gas phase, as non-interacting system, and in the solid state within a hydrogen bonded network. With the support of density functional theory (DFT) simulations of the spectra, we have found that the H-bonds mainly affect the N 1s level of the amino group, leaving the N 1s level of the pyridine-like N mostly unperturbed. This fact is responsible for a reduction of the chemical shift between the two XPS N 1s levels, compared to the free melamine. Consequently, N K-edge NEXAFS resonances involving the amino N 1s level also shift to lower photon energies. Moreover, the solid state absorption spectra have shown strong modification/quenching of resonances related with transitions from the amino N 1s level towards σ*orbitals involving the -NH2 terminations.
10.	Lanzilotto, Valeria, et al. (author) Spectroscopic Fingerprints of Intermolecular H-Bonding Interactions in Carbon Nitride Model Compounds 2018 In: Chemistry - A European Journal. - : Wiley-VCH Verlagsgesellschaft. - 0947-6539 .- 1521-3765. ; 24:53, s. 14198-14206 Journal article (peer-reviewed)abstract The effect of intermolecular H-bonding interactions on the local electronic structure of N-containing functional groups (amino group and pyridine-like N) that are characteristic of polymeric carbon nitride materials p-CN(H), a new class of metal-free organophotocatalysts, was investigated. Specifically, the melamine molecule, a building block of p-CN(H), was characterized by X-ray photoelectron (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecule was studied as a noninteracting system in the gas phase and in the solid state within a H-bonded network. With the support of DFT simulations of the spectra, it was found that the H-bonds mainly affect the N1s level of the amino group, leaving the N1s level of the pyridine-like N mostly unperturbed. This is responsible for a reduction of the chemical shift between the two XPS N1s levels relative to free melamine. Consequently, N K-edge NEXAFS resonances involving the amino N1s level also shift to lower photon energies. Moreover, the solid-state absorption spectra showed significant modification/quenching of resonances related to transitions from the amino N1s level to sigma* orbitals involving the NH2 termini.
11.	Man, Gabriel, et al. (author) Electronic coupling between the unoccupied states of the organic and inorganic sublattices of methylammonium lead iodide : A hybrid organic-inorganic perovskite single crystal 2021 In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 104:4 Journal article (peer-reviewed)abstract Organic-inorganic halide perovskites have been intensively reinvestigated due to their applications, yet the optoelectronic function of the organic cation remains unclear. Through organic-selective resonant Auger electron spectroscopy measurements on well-defined single-crystal surfaces, we find evidence for electronic coupling in the unoccupied states between the organic and inorganic sublattices of the prototypical hybrid perovskite, which is contrary to the notion based on previous studies that the organic cation is electronically inert. The coupling is relevant for electron dynamics in the material and for understanding optoelectronic functionality.
12.	Marks, Kess, et al. (author) Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111) 2019 In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 150:24 Journal article (peer-reviewed)abstract The temperature dependent dehydrogenation of naphthalene on Ni(111) has been investigated using vibrational sum-frequency generation spectroscopy, X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory with the aim of discerning the reaction mechanism and the intermediates on the surface. At 110 K, multiple layers of naphthalene adsorb on Ni(111); the first layer is a flat lying chemisorbed monolayer, whereas the next layer(s) consist of physisorbed naphthalene. The aromaticity of the carbon rings in the first layer is reduced due to bonding to the surface Ni-atoms. Heating at 200 K causes desorption of the multilayers. At 360 K, the chemisorbed naphthalene monolayer starts dehydrogenating and the geometry of the molecules changes as the dehydrogenated carbon atoms coordinate to the nickel surface; thus, the molecule tilts with respect to the surface, recovering some of its original aromaticity. This effect peaks at 400 K and coincides with hydrogen desorption. Increasing the temperature leads to further dehydrogenation and production of H-2 gas, as well as the formation of carbidic and graphitic surface carbon. Published under license by AIP Publishing.
13.	Sloboda, Tamara, et al. (author) A method for studying pico to microsecond time-resolved core-level spectroscopy used to investigate electron dynamics in quantum dots 2020 In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1 Journal article (peer-reviewed)abstract Time-resolved photoelectron spectroscopy can give insights into carrier dynamics and offers the possibility of element and site-specific information through the measurements of core levels. In this paper, we demonstrate that this method can access electrons dynamics in PbS quantum dots over a wide time window spanning from pico- to microseconds in a single experiment carried out at the synchrotron facility BESSY II. The method is sensitive to small changes in core level positions. Fast measurements at low pump fluences are enabled by the use of a pump laser at a lower repetition frequency than the repetition frequency of the X-ray pulses used to probe the core level electrons: Through the use of a time-resolved spectrometer, time-dependent analysis of data from all synchrotron pulses is possible. Furthermore, by picosecond control of the pump laser arrival at the sample relative to the X-ray pulses, a time-resolution limited only by the length of the X-ray pulses is achieved. Using this method, we studied the charge dynamics in thin film samples of PbS quantum dots on n-type MgZnO substrates through time-resolved measurements of the Pb 5d core level. We found a time-resolved core level shift, which we could assign to electron injection and charge accumulation at the MgZnO/PbS quantum dots interface. This assignment was confirmed through the measurement of PbS films with different thicknesses. Our results therefore give insight into the magnitude of the photovoltage generated specifically at the MgZnO/PbS interface and into the timescale of charge transport and electron injection, as well as into the timescale of charge recombination at this interface. It is a unique feature of our method that the timescale of both these processes can be accessed in a single experiment and investigated for a specific interface.
14.	Sloboda, Tamara, et al. (author) Photovoltage Generation across Different Interfaces in a PbS QuantumDot Solar Cell Investigated by Time-Resolved PhotoelectronSpectroscopy Other publication (other academic/artistic)abstract Quantum dot solar cells have not yet achieved optimal device performances and to direct development there is thereforea need to understand the device function of present solar cell structures in more detail. Understanding where photovoltage isgenerated in a device and where energy losses occur is a key aspect of this. We have previously shown that time-resolved core levelphotoelectron spectroscopy can be used to follow the photovoltage rise and decay at a specific interface from pico- to microsecondtimescales. Here, we extend this study and investigate the photovoltage generation in different parts of a PbS quantum dot solar cellthrough sample design. We show that thick absorbing quantum dot layers are required for generating a high photovoltage at theinterface between n-type PbS quantum dots and p-type quantum dots. Furthermore, we show that the full photovoltage is only generatedwhen a gold contact is deposited on the quantum dots and that the presence of this contact also leads to significantly slowercharge recombination.
15.	Sorgenfrei, Nomi L. A. N., et al. (author) Photodriven Transient Picosecond Top-Layer Semiconductor to Metal Phase-Transition in p-Doped Molybdenum Disulfide 2021 In: Advanced Materials. - : John Wiley & Sons. - 0935-9648 .- 1521-4095. ; 33:14 Journal article (peer-reviewed)abstract Visible light is shown to create a transient metallic S-Mo-S surface layer on bulk semiconducting p-doped indirect-bandgap 2H-MoS2. Optically created electron-hole pairs separate in the surface band bending region of the p-doped semiconducting crystal causing a transient accumulation of electrons in the surface region. This triggers a reversible 2H-semiconductor to 1T-metal phase-transition of the surface layer. Electron-phonon coupling of the indirect-bandgap p-doped 2H-MoS2 enables this efficient pathway even at a low density of excited electrons with a distinct optical excitation threshold and saturation behavior. This mechanism needs to be taken into consideration when describing the surface properties of illuminated p-doped 2H-MoS2. In particular, light-induced increased charge mobility and surface activation can cause and enhance the photocatalytic and photoassisted electrochemical hydrogen evolution reaction of water on 2H-MoS2. Generally, it opens up for a way to control not only the surface of p-doped 2H-MoS2 but also related dichalcogenides and layered systems. The findings are based on the sensitivity of time-resolved electron spectroscopy for chemical analysis with photon-energy-tuneable synchrotron radiation.
16.	Svanström, Sebastian, et al. (author) Effect of halide ratio and Cs+ addition on the photochemical stability of lead halide perovskites 2018 In: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 6:44, s. 22134-22144 Journal article (peer-reviewed)abstract Lead halide perovskite solar cells with multi-cation/mixed halide materials now give power conversion efficiencies of more than 20%. The stability of these mixed materials has been significantly improved through the addition of Cs+ compared to the original methylammonium lead iodide. However, it remains one of the most significant challenges for commercialisation. In this study, we use photoelectron spectroscopy (PES) in combination with visible laser illumination to study the photo-stability of perovskite films with different compositions. These include Br : I ratios of 50 : 50 and 17 : 83 and compositions with and without Cs+. For the samples without Cs and the 50 : 50 samples, we found that the surface was enriched in Br and depleted in I during illumination and that some of the perovskite decomposed into Pb-0, organic halide salts, and iodine. After illumination, both of these reactions were partially reversible. Furthermore, the surfaces of the films were enriched in organic halide salts indicating that the cations were not degraded into volatile products. With the addition of Cs+ to the samples, photo-induced changes were significantly suppressed for a 50 : 50 bromide to iodide ratio and completely suppressed for perovskites with a 17 : 83 ratio at light intensities exceeding 1 sun equivalent.
17.	Svanström, Sebastian, et al. (author) Effect of halide ratio and Cs+ addition on the photochemical stability of lead halide perovskites 2018 In: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 6:44, s. 22134-22144 Journal article (peer-reviewed)abstract Lead halide perovskite solar cells with multi-cation/mixed halide materials now give power conversion efficiencies of more than 20%. The stability of these mixed materials has been significantly improved through the addition of Cs+ compared to the original methylammonium lead iodide. However, it remains one of the most significant challenges for commercialisation. In this study, we use photoelectron spectroscopy (PES) in combination with visible laser illumination to study the photo-stability of perovskite films with different compositions. These include Br : I ratios of 50 : 50 and 17 : 83 and compositions with and without Cs+. For the samples without Cs and the 50 : 50 samples, we found that the surface was enriched in Br and depleted in I during illumination and that some of the perovskite decomposed into Pb0, organic halide salts, and iodine. After illumination, both of these reactions were partially reversible. Furthermore, the surfaces of the films were enriched in organic halide salts indicating that the cations were not degraded into volatile products. With the addition of Cs+ to the samples, photo-induced changes were significantly suppressed for a 50 : 50 bromide to iodide ratio and completely suppressed for perovskites with a 17 : 83 ratio at light intensities exceeding 1 sun equivalent.
18.	Teng, Zhang, et al. (author) Exploring the electronic structure of CoPc by photoemission and absorption spectroscopy Other publication (other academic/artistic)abstract Photoelectron spectroscopy and X-ray absorption spectroscopy were used to investigate the occupied and empty density of states of cobalt phthalocyanine (CoPc) in the gas phase and in thin films of different thicknesses, deposited onto a Au (111) single crystal. The comparison between experimental gas phase results and density functional theory single molecule simulations confirmed that the CoPc ground state is correctly described by the 2A1g electronic configuration. Moreover, the atomic character of the highest occupied molecular orbital of CoPc was addressed by performing photon energy dependent valence photoemission spectroscopy experiments on both CoPc gas phase and film samples. Our results clearly show that the highest occupied molecular orbital is derived only from the organic ligand, with mainly contribution from the carbon atoms. Multiplet ligand field theory was employed to simulate the Co L edge X-ray absorption spectroscopy results.
19.	Villamayor, Michelle Marie S., et al. (author) Wafer-sized WS2 monolayer deposition by sputtering 2022 In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 14:17, s. 6331-6338 Journal article (peer-reviewed)abstract We demonstrate that tungsten disulphide (WS2) with thicknesses ranging from monolayer (ML) to several monolayers can be grown on SiO2/Si, Si, and Al2O3 by pulsed direct current-sputtering. The presence of high quality monolayer and multilayered WS2 on the substrates is confirmed by Raman spectroscopy since the peak separations between the A(1g)-E-2g and A(1g)-2LA vibration modes exhibit a gradual increase depending on the number of layers. X-ray diffraction confirms a textured (001) growth of WS2 films. The surface roughness measured with atomic force microscopy is between 1.5 and 3 angstrom for the ML films. The chemical composition WSx (x = 2.03 +/- 0.05) was determined from X-ray Photoelectron Spectroscopy. Transmission electron microscopy was performed on a multilayer film to show the 2D layered structure. A unique method for growing 2D layers directly by sputtering opens up the way for designing 2D materials and batch production of high-uniformity and high-quality (stochiometric, large grain sizes, flatness) WS2 films, which will advance their practical applications in various fields.
20.	Zhang, Xiaoliang, et al. (author) Probing and Controlling Surface Passivation of PbS Quantum Dot Solid for Improved Performance of Infrared Absorbing Solar Cells 2019 In: Chemistry of Materials. - : AMER CHEMICAL SOC. - 0897-4756 .- 1520-5002. ; 31:11, s. 4081-4091 Journal article (peer-reviewed)abstract Surface properties of colloidal quantum dots (CQDs) are critical for the transportation and recombination of the photoinduced charge carrier in CQD solar cells, therefore dominating the photovoltaic performance. Herein, PbS CQD passivated using liquid-state ligand exchange (LSLX) and solid-state ligand exchange (SSLX) strategies are in detail investigated using photoelectron spectroscopy (PES), and solar cell devices are prepared to understand the link between the CQD surface properties and the solar cell function. PES using different energies in the soft and hard Xray regime is applied to study the surface and bulk properties of the CQDs, and the results show more effective surface passivation of the CQDs prepared with the LSLX strategy and less formation of lead-oxide. The CQD solar cells prepared with LSLX strategy show higher performance, and the photoelectric measurements suggest that the recombination of photoinduced charges is reduced for the solar cell prepared with the LSLX approach. Meanwhile, the fabricated solar cells exhibit good stability. This work provides important insights into how to fine-tune the CQD surface properties by improving the CQD passivation, and how this is linked to further improvements of the device photovoltaic performance.
21.	Zhang, Yu, et al. (author) Extreme ultraviolet photoemission of a tin-based photoresist 2021 In: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 118:17 Journal article (peer-reviewed)abstract Tin is a suitable element for inclusion in extreme ultraviolet photoresists because of its relatively high-absorption cross section at 92eV. The electrons emitted after photon absorption are expected to generate secondary electrons in the solid film. In this way, several pathways lead to reactive species that cause a solubility switch. Here, we report the photoelectron spectra of tin oxo cage photoresists over the photon energy range 60-150eV, and the relative yields of photoelectrons from the valence band of the resist, from the Sn 4d orbitals, and of inelastically scattered electrons. The experimental excitation spectra differ considerably from those predicted by commonly used database cross section values, and from the combined computed subshell spectra: the maximum efficiency of ionization of Sn 4d both in the photoresists and in Sn metal occurs near the industrially relevant EUV wavelength of 13.5nm.

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