Article
Chemistry, Physical
Zhaofu Zhang, Yuzheng Guo, John Robertson
Summary: Semiconducting oxides have significant applications, but the lack of p-type oxides with similar high mobility is a challenge. In this study, a promising p-type oxide SnTa2O6 is identified using high-throughput calculations, and other oxide properties are compared. Furthermore, p-type conductivity is observed in related niobium compounds.
CHEMISTRY OF MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yaguang Wang, Xu Shi, Tomoya Oshikiri, Hiroaki Misawa
Summary: We fabricated a novel photoanode structure that efficiently enhances light absorption and electron transfer through modal strong coupling, enabling water splitting at zero bias potential.
NANOSCALE ADVANCES
(2022)
Article
Materials Science, Multidisciplinary
F. Guo, M. Liu, J. Zhu, Z. Liu, Y. Zhu, M. Guo, X. Dong, Q. Zhang, Y. Zhang, W. Cai, J. Sui
Summary: This study demonstrates a method to control the crystal structure by manipulating lone pair expression, and successfully prepares LiBiTe2-doped GeTe with competitive thermoelectric properties. The results show that reducing the stereochemical activity of cation lone-pair electrons in GeTe is an effective strategy to achieve a room-temperature cubic structure.
MATERIALS TODAY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Ognjen Malkoc, Peter Stano, Daniel Loss
Summary: Theoretically investigating charge-noise-induced spin dephasing of a hole confined in a quasi-two-dimensional silicon quantum dot, the study found that higher-order corrections to the Luttinger Hamiltonian can create "sweet spots" to boost hole-spin dephasing time significantly. The device details, including dot size and asymmetry, growth direction, and applied magnetic and electric fields, play a crucial role in determining the location of these "sweet spots".
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Akinobu Nakada, Daichi Kato, Ryky Nelson, Hikaru Takahira, Masayoshi Yabuuchi, Masanobu Higashi, Hajime Suzuki, Maria Kirsanova, Naoji Kakudou, Cedric Tassel, Takafumi Yamamoto, Craig M. Brown, Richard Dronskowski, Akinori Saeki, Artem Abakumov, Hiroshi Kageyama, Ryu Abe
Summary: The study shows that by altering the Bi2MO4Cl compound with triple-layered Bi2MO4 blocks, the conduction band can be extensively controlled through a series of chain structures, resulting in changes in the conduction band minimum. Bi2YO4Cl exhibits higher photoconductivity and potential as an efficient visible-light photocatalyst for water splitting.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Energy & Fuels
Daniel Fritsch, Susan Schorr
Summary: Recent advances in exchange and correlation functionals in density functional theory calculations, together with powerful computing facilities, have made predictive computational materials science a reality. Climbing Jacob's ladder by using more accurate functionals improves result quality but also requires higher computational demands, particularly important for materials with incorrectly described electronic ground state properties.
JOURNAL OF PHYSICS-ENERGY
(2021)
Article
Materials Science, Multidisciplinary
Hassan Allami, Jacob J. Krich
Summary: The study focuses on the modification of band structures and the impact on plasmons in Highly Mismatched Alloys (HMAs) due to the introduction of alloying elements. The distribution of states in the split bands causes plasmons in HMAs to behave differently than in standard materials. The effective mass of the lower split band changes with alloy fraction, affecting the plasmon frequency in a unique way compared to traditional materials.
Article
Engineering, Environmental
Xiaobo Bai, Chengyan Liu, Fucong Li, Zhongwei Zhang, Ying Peng, Ruifan Si, Baoquan Feng, Guojing Wu, Jie Gao, Haiqiao Wei, Lei Miao
Summary: This study demonstrates that the power factor (PF) of GeTe can be greatly enhanced by tailoring the interaction between Te 5s2 lone pair and antibonding orbitals. By hybridizing Zr 4d2 electrons with the antibonding orbitals, the contribution of Ge 4s2 electrons to the valence band is promoted, resulting in band sharpening in the rhombohedral phase and simultaneous band sharpening and flattening in the cubic phase. This leads to increased carrier mobility and Seebeck coefficient, improving the maximum PF and achieving a peak zT value of -1.9 at 673 K.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Physical
Wanda Navarra, Ida Ritacco, Olga Sacco, Lucia Caporaso, Matteo Farnesi Camellone, Vincenzo Venditto, Vincenzo Vaiano
Summary: The beneficial effects of doping and heterojunctions on the photo-catalytic activity of ZnO and TiO2 were investigated. The presence of ZnO and N-doped TiO2 in the heterojunction resulted in a decrease in band gap energy and improved photocatalytic performance compared to N-doped TiO2 and ZnO alone.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Review
Chemistry, Multidisciplinary
Mei Yan, Huai-Guo Xue, Sheng-Ping Guo
Summary: In the past 20 years, extensive research has been conducted on novel nonlinear optical (NLO) compounds, laying an important foundation for the application of NLO materials. This review summarizes MIR NLO materials containing lone-pair cations and discusses their chemical compositions and NLO properties.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Physics, Applied
Yasutomo Kajikawa
Summary: Deconvolution analysis of the temperature-dependent reduction in activation energy of conductivity has been used to identify hopping conduction mechanism in FeSi samples. It is found that hopping conduction in the top impurity Hubbard band, epsilon(2) conduction, significantly affects the conductivity around 50 K. Additionally, an increase in the effective concentration of hopping carriers in the bottom Hubbard band leads to a step-like increase in variable range hopping conductivity with rising temperature in FeSi samples when compensation ratio is less than 0.2.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2022)
Article
Nanoscience & Nanotechnology
Tzung-En Hsieh, Johannes Frisch, Regan G. Wilks, Marcus Baer
Summary: This study investigates the surface properties of gallium and gallium oxide, as well as the evolution of the surface structure during oxidation and reduction at high temperature. The formation of a substoichiometric Ga2O3-delta layer on the surface of gallium nanoparticles is found to be dependent on oxidation time. Furthermore, annealing at elevated temperatures can efficiently remove the Ga2O3-delta layer.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Sergey S. Krishtopenko, Frederic Teppe
Summary: Using an elegant model involving only Gamma(6c) and Gamma(8v) bands, the authors found that Kane fermions are two nested Dirac particles. Studying their behavior in crossed electric and magnetic fields, it was observed that Kane fermions decay into two independent Dirac particles with increase of the electric field.
Article
Chemistry, Physical
Yanan Wang, Jing Jin, Hao Ma, Meng Zhang, Qianwen Li, He Wang, Bing Zhao, Weidong Ruan, Guan Yan
Summary: This study investigates the importance of enhancing charge transfer in the AZO/MPy/Ag sandwich structure, and identifies a significant CT route from the CB of AZO to the LUMO of the MPy molecule, which can effectively improve the degree of CT. This discovery is expected to play a crucial role in enhancing SERS.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Physics, Multidisciplinary
Leon C. Camenzind, Simon Svab, Peter Stano, Liuqi Yu, Jeramy D. Zimmerman, Arthur C. Gossard, Daniel Loss, Dominik M. Zumbuhl
Summary: In this experiment, isotropic and anisotropic g-factor corrections in lateral GaAs single-electron quantum dots were determined by extracting the Zeeman splitting through measuring tunnel rates in individual spin states for various strengths and directions of an in-plane magnetic field. The linear dependence of Zeeman energy on magnetic field strength allowed for the extraction of the g-factor, which was understood in terms of spin-orbit interaction induced corrections to the GaAs bulk g-factor. Experimental detection and identification of minute band-structure effects in the g-factor in GaAs quantum dots are significant for spin qubits research.
PHYSICAL REVIEW LETTERS
(2021)
Article
Energy & Fuels
Max Hilaire Wolter, Romain Carron, Enrico Avancini, Benjamin Bissig, Thomas Paul Weiss, Shiro Nishiwaki, Thomas Feurer, Stephan Buecheler, Philip Jackson, Wolfram Witte, Susanne Siebentritt
Summary: Band tails have a significant impact on the power conversion efficiency of solar cells, particularly in relation to the open-circuit voltage loss. By incorporating alkali atoms, band tails can be deliberately adjusted to improve efficiency in thin-film solar cells. The presence of band tails increases radiative recombination and nonradiative recombination losses in solar cells.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Nanoscience & Nanotechnology
Mohit Sood, Jakob Bombsch, Alberto Lomuscio, Sudhanshu Shukla, Claudia Hartmann, Johannes Frisch, Wolfgang Bremsteller, Shigenori Ueda, Regan G. Wilks, Marcus Baer, Susanne Siebentritt
Summary: In devices based on Zn(O,S)/CuInS2, interface recombination is mainly caused by defects near the interface rather than unfavorable energy-level alignment or Fermi-level pinning. Research has shown that the dominant recombination channel is present at the Zn(O,S)/CuInS2 interface.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Evandro Martin Lanzoni, Omar Ramirez, Himanshu Phirke, Amala Elizabeth, Harry Moenig, Alex Redinger
Summary: Alkali post-deposition treatments (PDTs) have been shown to improve the power conversion efficiency of thin-film solar cells, with potassium effectively diffusing into the bulk of epitaxial CIGSe absorber layers. The diffusion of potassium depends on the Cu content of the absorbers, with Cu-depleted films showing higher diffusion rates for K. These treatments also increase PL yield, suggesting passivation of defects or increased doping.
Article
Nanoscience & Nanotechnology
Yong Ding, Bin Ding, Hiroyuki Kanda, Onovbaramwen Jennifer Usiobo, Thibaut Gallet, Zhenhai Yang, Yan Liu, Hao Huang, Jiang Sheng, Cheng Liu, Yi Yang, Valentin Ianis Emmanuel Queloz, Xianfu Zhang, Jean-Nicolas Audinot, Alex Redinger, Wei Dang, Edoardo Mosconic, Wen Luo, Filippo De Angelis, Mingkui Wang, Patrick Doerflinger, Melina Armer, Valentin Schmid, Rui Wang, Keith G. Brooks, Jihuai Wu, Vladimir Dyakonov, Guanjun Yang, Songyuan Dai, Paul J. Dyson, Mohammad Khaja Nazeeruddin
Summary: The incorporation of electron transport layers based on single-crystalline TiO2 rhombohedral nanoparticles enables the realization of stable and efficient large-area perovskite solar cell modules. The devices achieve high efficiency and stability, making them promising for practical applications.
NATURE NANOTECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
Amala Elizabeth, Sudhir K. Sahoo, Himanshu Phirke, Tim Kodalle, Thomas D. Kuhne, Jean-Nicolas Audinot, Tom Wirtz, Alex Redinger, Christian A. Kaufmann, Hossein Mirhosseini, Harry Moenig
Summary: Alkali postdeposition treatments of Cu(In,Ga)Se-2 absorbers with KF, RbF, and CsF have been effective in improving the efficiency of chalcopyrite thin film solar cells. This study investigates the impact of RbF treatment on the electronic properties and defect physics of chalcopyrite absorber surfaces, showing that RbF treatment can effectively passivate electronic defect levels and prevent surface oxidation. X-ray photoelectron spectroscopy data reveals the presence of chemisorbed Rb on the surface, contributing to the surface passivation. Additionally, the diffusion of Rb along with other elements and the subsequent heat-induced formation of metallic Rb phases can lead to deterioration of the absorber-window interface.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Nanoscience & Nanotechnology
Jonathan Rommelfangen, Sven Reichardt, Van Ben Chu, Ludger Wirtz, Phillip J. Dale, Alex Redinger
Summary: This study investigates the impact of strain and temperature on the growth mode of mono- and few-layer MoS2 grown on Muscovite mica. The results show that the determination of the number of MoS2 layers based solely on Raman spectroscopy is misleading due to strain and changes in growth mode. By combining atomic force microscopy, Raman spectroscopy, and ab initio calculations, it is revealed that the growth at 500 degrees C exhibits strained layer-by-layer growth up to three mono-layers, while at 700 degrees C, a strain release occurs and layer-by-layer growth is confined to the first mono-layer.
Article
Nanoscience & Nanotechnology
Omar Ramirez, Evandro Martin Lanzoni, Ricardo G. Poeira, Thomas P. Weiss, Renaud Leturcq, Alex Redinger, Susanne Siebentritt
Summary: Doping in chalcopyrite Cu(In,Ga)Se-2 is determined by intrinsic point defects. N-type and P-type conductivities can be achieved in CuInSe2 depending on growth conditions, while CuGaSe2 always behaves as a P-type semiconductor. The N-to-P transition in Cu-poor Cu(In,Ga)Se-2 occurs when the gallium content reaches the critical concentration of 15%-19%.
Review
Physics, Multidisciplinary
S. Siebentritt, T. P. Weiss
Summary: Chalcopyrite solar cells play a crucial role in mitigating the climate crisis due to their low carbon emissions. Improvements in efficiency have been achieved through post-deposition treatments with heavy alkalis. However, limitations in open circuit voltage are caused by tail states and band gap distribution. Increased diode factor hampers further efficiency improvements due to metastable defect transitions. Alloying with Ag shows potential for band-edge engineering and diode factor enhancement. Passivation of the back contact in state-of-the-art cells has been extensively researched. Tandem cells are expected to significantly improve efficiency. Chalcopyrite solar cells show promising potential as both bottom and top cells.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Article
Chemistry, Multidisciplinary
Christian Kameni Boumenou, Himanshu Phirke, Jonathan Rommelfangen, Jean-Nicolas Audinot, Shiro Nishiwaki, Tom Wirtz, Romain Carron, Alex Redinger
Summary: Alkali post deposition treatments (PDTs) have been used to improve the power conversion efficiency (PCE) of Cu(In,Ga)Se-2 solar cell devices. However, a detailed understanding of how PDTs impact the nanoscale optoelectronic properties is still lacking. In this study, various scanning probe techniques and spectroscopy methods were used to show that RbF PDT treatments result in an exchange of Rb with Cu at the surface. The existence of the RbInSe2 phase is unlikely to be responsible for the recent improvements in PCE.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Applied
Thomas Paul Weiss, Omar Ramirez, Stefan Paetel, Wolfram Witte, Jiro Nishinaga, Thomas Feurer, Susanne Siebentritt
Summary: Cu(In,Ga)Se2-based solar cells achieve power conversion efficiencies exceeding 23%. However, the fill factor of these cells is relatively low due to diode factors greater than 1, mainly caused by metastable defects in the Cu(In,Ga)Se2 alloy. Excitation-dependent photoluminescence measurements reveal that the increased diode factor can be well explained by the model of metastable defects. Optically measured diode factors impose a lower limit on the electrical diode factor of finished solar cells. Ag alloying provides a pathway to increase fill factors and efficiencies for Cu(In,Ga)Se2-based solar cells.
PHYSICAL REVIEW APPLIED
(2023)
Article
Energy & Fuels
Omar Ramirez, Jiro Nishinaga, Felix Dingwell, Taowen Wang, Aubin Prot, Max Hilaire Wolter, Vibha Ranjan, Susanne Siebentritt
Summary: The detrimental effect of tail states on V-OC in Cu(In,Ga)Se-2 solar cells has been shown. Alkali metals can reduce tail states by passivating charged defects at grain boundaries. This study investigates the effect of compositional variations and alkali incorporation on tail states in Cu(In,Ga)Se-2 films. The results reveal that sodium and potassium can decrease the density of tail states, even in the absence of grain boundaries, suggesting additional mechanisms beyond grain boundaries for the alkali effects. Moreover, doping-induced increase in sodium or potassium incorporation contributes to the reduced tail states, which are primarily caused by electrostatic potential fluctuations and influenced by grain interior properties. By analyzing the voltage loss in high-efficiency polycrystalline and single crystalline devices, this work presents a comprehensive model explaining the voltage loss in Cu(In,Ga)Se-2 based on the combined effect of doping on tail states and V-OC.
Article
Nanoscience & Nanotechnology
Aubin JC. M. Prot, Michele Melchiorre, Felix Dingwell, Anastasia Zelenina, Hossam Elanzeery, Alberto Lomuscio, Thomas Dalibor, Maxim Guc, Robert Fonoll-Rubio, Victor Izquierdo-Roca, Gunnar Kusch, Rachel A. Oliver, Susanne Siebentritt
Summary: The article discusses the achievement of record efficiency in chalcopyrite-based solar cells using a gallium gradient and reveals non-radiative recombination issues at the back contacts of industrial absorbers. The study proposes a model where discrete bandgap phases interlace to form an apparent gradient throughout the thickness of the absorber.
Article
Chemistry, Physical
Susanne Siebentritt, Uwe Rau, Sevan Gharabeiki, Thomas P. Weiss, Aubin Prot, Taowen Wang, Damilola Adeleye, Marwan Drahem, Ajay Singh
Summary: Absolute photoluminescence measurements are an important tool for predicting the quality of photovoltaic absorber materials. The extraction methods of quasi Fermi level splitting suffer from systematic errors. Radiative efficiency and the generalized Planck's law provide reliable comparisons between different materials and allow the extraction of non-absolute absorptance spectrum.
FARADAY DISCUSSIONS
(2022)
Article
Chemistry, Physical
Mohit Sood, Damilola Adeleye, Sudhanshu Shukla, Tobias Torndahl, Adam Hultqvist, Susanne Siebentritt
Summary: Cu(In,Ga)S-2 has the potential to be a prime candidate for the top cell in tandem solar cells due to its tunable bandgap and favorable electronic properties. This study explores the use of low-temperature atomic layer deposited (Zn,Sn)O thin film as a buffer layer to improve the optoelectronic and electrical characteristics of the devices, achieving a 14% PCE.
FARADAY DISCUSSIONS
(2022)
Article
Chemistry, Physical
Stener Lie, Maxim Guc, Venkatesh Tunuguntla, Victor Izquierdo-Roca, Susanne Siebentritt, Lydia Helena Wong
Summary: In this study, CXTS (X = Zn, Mn, Mg, Ni, Fe, Co, Ba, Sr) thin films are synthesized and their physical properties and device performance are compared, leading to the discovery of promising solar cell absorbers.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)
