Review
Nanoscience & Nanotechnology
Buyang Yu, Chunfeng Zhang, Lan Chen, Zhengyuan Qin, Xinyu Huang, Xiaoyong Wang, Min Xiao
Summary: Perovskite semiconductor nanocrystals have shown promise in optoelectronic applications, with recent research focusing on their photoinduced carrier dynamics. The dynamics of carrier generation, recombination, and transport play essential roles in the performance of devices such as light-emitting diodes and solar cells. Spin dynamics and coherent exciton dynamics are important for potential applications in quantum information technology, though there are still controversial results and unresolved origins to be addressed.
Review
Nanoscience & Nanotechnology
Buyang Yu, Chunfeng Zhang, Lan Chen, Zhengyuan Qin, Xinyu Huang, Xiaoyong Wang, Min Xiao
Summary: Perovskite semiconductor nanocrystals have shown great potential in optoelectronic applications, and their performances rely on the excited-state dynamics, with recent studies focusing on photoinduced carrier dynamics, spin dynamics, and coherent exciton dynamics. Future research should aim to address controversial results and unresolved origins to fully understand the excited-state dynamics.
Article
Physics, Multidisciplinary
Zemin Xu, Jiandong Yao, Guowei Yang, Tianshu Lai
Summary: The ultrafast dynamics of photoexcited carriers and coherent phonons in ultrathin Bi2Te3 thermoelectric films were investigated. A low-frequency coherent optical phonon was observed in the ultrathin films, which divided the films into different groups and potentially reduced the thermal conductivity. The dominance of carrier-carrier scattering in thermalization processes provides insights into the high electrical conductivity and power factor of ultrathin Bi2Te3 films at room temperature.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2022)
Article
Materials Science, Multidisciplinary
Yicun Chen, Tianyu Shu, Tianshu Lai, Huizhen Wu
Summary: This study examined the ultrafast dynamics of photoexcited carriers in an intrinsic CdTe film using femtosecond-resolved pump-probe transient differential transmission spectroscopy. A dynamic model was developed to analyze the thermalization, cooling, and recombination processes of the photoexcited carriers. The results showed that carrier thermalization time increased with carrier density and decreased with excess energy, while carrier cooling strongly depended on carrier density and excess energy, with cooling time varying from 0.2 to 5 ps. Furthermore, carrier recombination in the intrinsic CdTe film was dominated by radiative recombination of electron-hole pairs.
RESULTS IN PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Valerio Campanari, Daniele Catone, Patrick O'Keeffe, Alessandra Paladini, Stefano Turchini, Faustino Martelli, Matteo Salvato, Nouha Loudhaief, Elena Campagna, Paola Castrucci
Summary: Carrier dynamics in polycrystalline Bi2Se3 topological insulator thin films were studied using femtosecond transient absorption spectroscopy. The observed absorption bleaching signals can be attributed to electronic transitions involving both bulk and surface states in the complex Bi2Se3 band structure. The differences in rise times of the bleaching signals provide insights into the band filling dynamics and the efficient population of surface topological states by carrier-phonon scattering.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Physics, Applied
Fang Bian, XinGe Wu, Shuai Shao, XiangYing Meng, GaoWu Qin
Summary: Photo-carrier relaxation is important for the efficiency of semiconductor photon-conversion, and impurities can improve the efficiency and stability of perovskites. Through theoretical calculations and simulations, we explored the effects of Sr-doping and O-vacancies on the electronic band structure and photoexcited carrier cooling in LaCoO3. We found that Sr-doping induces a semiconductor-metal transition, while O-vacancies restore semiconductor properties. Additionally, O-vacancies significantly affect the electronic band structure, leading to reduced photo-electron cooling. Our findings provide insight into the functions of impurities in perovskites and can contribute to the development of practical photo-conversion technologies.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Lei Gao, Zhenliang Hu, Junpeng Lu, Hongwei Liu, Zhenhua Ni
Summary: Two-dimensional transition metal dichalcogenides (TMDs) show great potential in optoelectronics, with the performance of TMD materials and devices depending significantly on processes related to photoelectric conversion. Defects in materials can affect these processes, leading to new photoelectric conversion channels. Ultrafast spectroscopies have been used to explore transient signals caused by defects in TMDs, aiding in material design and performance optimization.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Multidisciplinary Sciences
Hao-Wen Liu, Wen-Hao Liu, Zhao-Jun Suo, Zhi Wang, Jun-Wei Luo, Shu-Shen Li, Lin-Wang Wang
Summary: This study utilizes the real-time time-dependent density functional theory method to track the motion of individual vanadium ions in VO2 during photoinduced phase transition (PIPT). The results reveal that the coherent or disordered dynamics of the vanadium ions can be manipulated by tuning the laser fluence. The competing forces of photoexcited holes and thermal-induced vibrations determine the nature of the PIPT process. The interference of thermal phonons leads to a disordered PIPT process when the laser fluence is weak, while the saturation of photoexcited holes limits the timescale of PIPT when the laser fluence is strong.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Multidisciplinary Sciences
Jiyu Xu, Daqiang Chen, Sheng Meng
Summary: Photoexcitation has been proven as an efficient way to trigger phase transitions in strongly correlated materials. However, the atomistic mechanisms behind the structural phase transitions (SPTs) and electronic insulator-metal transitions (IMTs) in VO2 have been controversial. This study clarifies some key controversies and provides insights into the underlying atomistic processes and decoupling nature of photoinduced SPT and IMT in nonequilibrium states.
Article
Chemistry, Physical
Shimpei Naniwa, Kosaku Kato, Akira Yamamoto, Hisao Yoshida, Akira Yamakata
Summary: Heterogeneous photocatalysis is a promising technology for artificial photosynthesis and environmental remediation. Understanding trap states of photoexcited carriers is crucial for the development of efficient photocatalysts. This study found that the depth of electron traps on anatase TiO2 nanoparticles decreases with increasing particle size.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Multidisciplinary
Sheng-Nan Zhu, Shun-Cai Zhao, Lin-Jie Chen, Qing Fang
Summary: This study evaluates the transfer qualities of photoexcited carriers in doped DQDs photocells and finds that certain structure parameters caused by doping can significantly control the transfer properties. Additionally, slightly increasing the ambient temperature benefits the transfer performance in this doping DQDs photocell model.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Materials Science, Multidisciplinary
Aswathi K. Sivan, Lorenzo Di Mario, Yunyan Zhang, Daniele Catone, Patrick O'Keeffe, Stefano Turchini, Valentina Mussi, Huiyun Liu, Faustino Martelli
Summary: Thinner semiconductor nanowires show easier buildup of hot-phonon bottleneck due to increased phonon scattering at the sidewalls, leading to higher carrier temperature compared to thicker nanowires. This indicates that phonon-mediated scattering processes play a major role in thin nanowires at the investigated carrier densities.
Article
Chemistry, Multidisciplinary
Christian Heyn, Leonardo Ranasinghe, Ahmed Alshaikh, Carlos A. Duque
Summary: This study investigates the optical emission of cone-shell quantum structures (CSQS) under vertical electric and magnetic fields using simulations. The unique shape of CSQS undergoes a transformation from a disk into a quantum-ring with a tunable radius under an electric field. The influence of an additional magnetic field is also examined.
Article
Chemistry, Multidisciplinary
Samantha M. Harvey, Daniel W. Houck, Wen Liu, Yuzi Liu, David J. Gosztola, Brian A. Korgel, Michael R. Wasielewski, Richard D. Schaller
Summary: CuInSe2 nanocrystals with tunable near-infrared bandgaps show potential for photovoltaic applications and as substitutes for toxic semiconductor compositions. The presence of ligands during synthesis introduces nonradiative electronic states, impacting carrier dynamics and leading to low photoluminescence quantum yields. Carrier lifetimes are influenced by the type of ligand, with rapid trapping observed in certain cases.
Article
Chemistry, Multidisciplinary
Aiqin Hu, Wei Liu, Xiaofang Li, Shengnan Xu, Yaolong Li, Zhaohang Xue, Jinglin Tang, Lulu Ye, Hong Yang, Ming Li, Yu Ye, Quan Sun, Qihuang Gong, Guowei Lu
Summary: Theoretically, the kinetic energy of photoelectrons from n-type regions was found to be higher than that of p-type regions due to different work functions. Surprisingly, the outer n-type regions exhibited higher kinetic energy compared to inner n-type regions, caused by reverse bias induced by photoemission. Time-resolved PEEM results showed varying evolution rates of hot electrons in different doping regions.
Article
Chemistry, Physical
Maxim Guc, Tim Kodalle, Ramya Kormath Madam Raghupathy, Hossein Mirhosseini, Thomas D. Kuehne, Ignacio Becerril-Romero, Alejandro Perez-Rodriguez, Christian A. Kaufmann, Victor Izquierdo-Roca
JOURNAL OF PHYSICAL CHEMISTRY C
(2020)
Article
Materials Science, Coatings & Films
Nikolaus Weinberger, David Stock, Christian Alexander Kaufmann, Tim Kodalle, Marc D. Heinemann, Daniel Huber, Martina Harnisch, Andreas Zimmermann, Georg N. Strauss, Roman Lackner
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2020)
Article
Energy & Fuels
Aleksandra Nikolaeva, Maximilian Krause, Norbert Schaefer, Wolfram Witte, Dimitrios Hariskos, Tim Kodalle, Christian A. Kaufmann, Nicolas Barreau, Daniel Abou-Ras
PROGRESS IN PHOTOVOLTAICS
(2020)
Article
Chemistry, Physical
Felix Lang, Marko Jost, Kyle Frohna, Eike Kohnen, Amran Al-Ashouri, Alan R. Bowman, Tobias Bertram, Anna Belen Morales-Vilches, Dibyashree Koushik, Elizabeth M. Tennyson, Krzysztof Galkowski, Giovanni Landi, Mariadriana Creatore, Bernd Stannowski, Christian A. Kaufmann, Juergen Bundesmann, Joerg Rappich, Bernd Rech, Andrea Denker, Steve Albrecht, Heinz-Christoph Neitzert, Norbert H. Nickel, Samuel D. Stranks
Article
Energy & Fuels
Tim Kodalle, Hasan A. Yetkin, Alejandra Villanueva Tovar, Tobias Bertram, Reiner Klenk, Rutger Schlatmann, Christian A. Kaufmann
Summary: A comprehensive device model for CIGSe thin-film solar cells based on numerical simulations is presented, which reproduces experimentally determined characteristics under different Rb-conditionings. The model highlights the impacts of Rb-treatment on the doping density, defect passivation, and photocurrent barrier formation within the CIGSe material.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Nikolaus Weinberger, David Stock, Jochen Mesle, Christian A. Kaufmann, Tobias Bertram, Tim Kodalle, Roland Wuerz, Daniel Huber, Andreas Zimmermann, Georg Strauss, Roman Lackner
Summary: This article presents a method for industrial roll-to-roll deposition of Cu(In,Ga)Se-2 thin films on stainless steel foil for use in flexible thin-film solar cells, achieving high conversion efficiency. The influence of different power settings of magnetron sputtering sources on gallium distribution and differences between static and R2R processes are studied.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Nanoscience & Nanotechnology
Nikolaus Weinberger, Tim Kodalle, Tobias Bertram, Rene Gunder, Andreas Saxer, Roman Lackner, Georg N. Strauss, Christian A. Kaufmann
Summary: In this study, Rb, In, and Se were deposited at various substrate temperatures, with RbInSe2 crystal phase detectable at 350 degrees C. Crystallization of monoclinic RbInSe2 was observed at 215 degrees C on the sample grown at the lowest temperature. The morphology of the layers and the preferred crystal orientation of the RISe layer changed with increasing substrate temperature.
SCRIPTA MATERIALIA
(2021)
Article
Green & Sustainable Science & Technology
Bunyamin Umsur, Natalia Maticiuc, Tim Kodalle, Robert Wenisch, Isheta Majumdar, Yajie Wang, Hasan A. Yetkin, Tobias Bertram, Christian A. Kaufmann, Rutger Schlatmann, Iver Lauermann
Summary: This paper compares the properties of CdS/CIGSe and Zn(O,S)/CIGSe interfaces depending on the absorber composition and the application of an RbF post deposition treatment. It was found that Zn(O,S)/CIGSe interface is less sensitive to changes of the CIGSe composition and to the RbF-PDT compared to the CdS/CIGSe interface. Additionally, the study revealed a strong correlation of Cd diffusion and concentration of VCu in CIGSe before the PDT.
Article
Energy & Fuels
Sinju Thomas, Tobias Bertram, Christian Kaufmann, Tim Kodalle, Jose A. Marquez Prieto, Hannes Hempel, Leo Choubrac, Wolfram Witte, Dimitrios Hariskos, Roland Mainz, Romain Carron, Jan Keller, Pablo Reyes-Figueroa, Reiner Klenk, Daniel Abou-Ras
Summary: In this study, the impacts of effective band-gap energy, electron diffusion length, and Ga/In gradient on the Gaussian broadening of parameters describing the EQE onset of thin-film solar cells were evaluated. The results show that the total standard deviation sigma(total) can be separated into contributions from these material properties and a residual component sigma(residual). It is demonstrated that a flat band-gap with no compositional gradient in the CIGSe absorber is essential to obtain the lowest sigma(total) values and thus result in lower recombination losses and gains in V-oc.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Chemistry, Multidisciplinary
Ivona Kafedjiska, Igal Levine, Artem Musiienko, Natalia Maticiuc, Tobias Bertram, Amran Al-Ashouri, Christian A. Kaufmann, Steve Albrecht, Rutger Schlatmann, Iver Lauermann
Summary: The performance of five hole-transporting layers (HTLs) in single-junction perovskite and Cu(In, Ga)Se-2 (CIGSe)-perovskite tandem solar cells was investigated. Among them, NiOx:Cu+SAM was found to be the most suitable HTL for the monolithic CIGSe-perovskite tandem devices. It exhibited superior interfacial charge-carrier dynamics and achieved a power-conversion efficiency of 23.4%, V-oc of 1.72V, and a fill factor of 71%.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Energy & Fuels
I Kafedjiska, G. Farias Basulto, F. Ruske, N. Maticiuc, T. Bertram, C. A. Kaufmann, R. Schlatmann, I Lauermann
Summary: We propose monolithic copper-indium-gallium-diselenide (Cu(In,Ga)Se-2, CIGSe)-perovskite tandem solar cells with NiOx:Cu as a hole-transporting layer (HTL) transferred in air or N-2. The tandem with N-2-transferred NiOx:Cu + SAM achieves a champion efficiency of 23.2%, V-oc of 1.69 V, and FF of 78.3%. Air-transferred NiOx:Cu + SAM samples exhibit V-oc and FF losses, while those without SAM have heavy shunts. Exposure to air leads to loss in Ni2+ species, changes in NiOx:Cu's work function and valence band maxima, negatively impacting the tandems' V-oc and FF. Various morphological defects are detected in tandems with poor performance, originating from defects in the bottom CIGSe cell or cracking/delaminating of the perovskite top cell. The NiOx:Cu + SAM HTL bi-layer can decouple the growth of the top device from the rough, defect-rich and defect-tolerant bottom device, enabling high-performing devices.
JOURNAL OF PHYSICS-ENERGY
(2023)
Article
Materials Science, Multidisciplinary
Amala Elizabeth, Hauke Conradi, Sudhir K. Sahoo, Tim Kodalle, Christian A. Kaufmann, Thomas D. Kuehne, Hossein Mirhosseini, Daniel Abou-Ras, Harry Moenig
Article
Energy & Fuels
Alejandra Villanueva-Tovar, Tim Kodalle, Christian A. Kaufmann, Rutger Schlatmann, Reiner Klenk
Article
Chemistry, Multidisciplinary
Amran Al-Ashouri, Artiom Magomedov, Marcel Ross, Marko Jost, Martynas Talaikis, Ganna Chistiakova, Tobias Bertram, Jose A. Marquez, Eike Kohnen, Ernestas Kasparavicius, Sergiu Levcenco, Lidon Gil-Escrig, Charles J. Hages, Rutger Schlatmann, Bernd Rech, Tadas Malinauskas, Thomas Unold, Christian A. Kaufmann, Lars Korte, Gediminas Niaura, Vytautas Getautis, Steve Albrecht
ENERGY & ENVIRONMENTAL SCIENCE
(2019)
Article
Chemistry, Analytical
Tim Kodalle, Dieter Greiner, Varvara Brackmann, Karsten Prietzel, Anja Scheu, Tobias Bertram, Pablo Reyes-Figueroa, Thomas Unold, Daniel Abou-Ras, Rutger Schlatmann, Christian A. Kaufmann, Volker Hoffmann
JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY
(2019)
