Article
Energy & Fuels
Yun Jia, Youyang Wang, Xiaobo Hu, Jinjia Xu, Guoen Weng, Xianjia Luo, Shaoqiang Chen, Ziqiang Zhu, Hidefumi Akiyama
Summary: In this study, three types of breakdown phenomena in monocrystalline Si solar cells were observed using the reverse-biased electroluminescence imaging technique. Various methods were applied to diagnose each breakdown mechanism, including combining EL and ReBEL imaging, introducing distributed circuit modeling, analyzing temperature coefficient, Si energy band structure, Baraff theory, and identifying the Zener effect as a possible cause of early breakdown.
Article
Energy & Fuels
Pablo Martin, Jose Ramon Gonzalez, Ivan Garcia, Carlos Algora, Ignacio Rey-Stolle
Summary: In this study, reverse bias stress tests were conducted on triple-junction solar cells to analyze the changes in performance parameters and the underlying physical processes during degradation. It was found that the top GaInP subcell degrades suddenly at low reverse voltages.
PROGRESS IN PHOTOVOLTAICS
(2022)
Review
Energy & Fuels
Muhammad N. Sharif, Jingshu Yang, Xiaokun Zhang, Yehua Tang, Ke-Fan Wang
Summary: This article investigates the improvement of efficiency in crystalline silicon solar cells through the use of a proper top cell absorber in tandem solar cells. The current state, challenges, and potential solutions are evaluated. III-V semiconductors and chalcogenides are discussed as options for the top cell absorber, and various technical solutions are proposed.
Article
Materials Science, Multidisciplinary
Zhi-Yuan Yu, Yu-Chen Zhang, Shuai Li, Xi-Yuan Dai, Xia-Yan Xue, Hong Shen, Song -You Wang, Ming Lu
Summary: A synergistic approach of interface engineering is reported to efficiently improve the performance of silicon nanocrystal light-emitting diode (Si-NC LED). This method can significantly increase the brightness of the LED by improving charge injection and transport, and controlling the radiative recombination of the injected charges.
Article
Energy & Fuels
Timon Sebastian Vaas, Bart Elger Pieters, Andreas Gerber, Uwe Rau
Summary: The initial stages of hot-spot and defect creation in Cu(In,Ga)Se-2 solar cells due to reverse breakdown are not well understood. This study presents experimental evidence supporting the thesis that a positive feedback loop between local temperature and current density leads to thermal runaway and permanent damage.
IEEE JOURNAL OF PHOTOVOLTAICS
(2023)
Article
Energy & Fuels
Andrew M. Gabor, Philip J. Knodle, Maurice Covino, Joseph Fioresi, Dylan J. Colvin, Kristopher O. Davis
Summary: We analyzed over 4000 electroluminescence images of hail damaged solar panels and classified the defects into categories for insurance claims and resale pricing. The statistics can be useful for predicting invisible damage to solar systems.
IEEE JOURNAL OF PHOTOVOLTAICS
(2022)
Article
Astronomy & Astrophysics
Kenneth P. Dere
Summary: This article discusses the reconstruction of the differential emission measure (DEM) from observations of spectral line intensities. The analysis reveals that a set of emission-line intensities can only constrain a model consisting of four temperature-emission measure pairs, and a more complex model does not improve the fit.
ASTROPHYSICAL JOURNAL
(2022)
Article
Optics
Yu N. Nozdrin, A. Okomel'kov, E. A. Arkhipova, S. A. Kraev, V. S. Varavin
Summary: Within a simple two-band model, the behavior of nonequilibrium carriers in CdxHg1-xTe solid solutions under an external electric field is considered using the effective parameters method. It is found that under certain conditions, carriers can exhibit an inverse energy distribution and high amplification factors at direct interband transitions. Experimental studies on thick MCT films show responses to external pulsed electric fields and provide insight into potential prospects and challenges for obtaining a laser effect using interband breakdown in electric fields.
JOURNAL OF LUMINESCENCE
(2021)
Review
Chemistry, Physical
Michele De Bastiani, Anand S. Subbiah, Maxime Babics, Esma Ugur, Lujia Xu, Jiang Liu, Thomas G. Allen, Erkan Aydin, Stefaan De Wolf
Summary: Perovskite/silicon tandem solar cells are high-efficiency and low-cost photovoltaic devices that enhance stability and energy yield by collecting light from both the sunward and rear side.
Article
Energy & Fuels
Carlos Enrico Clement, Jai Prakash Singh, Erik Birgersson, Yan Wang, Yong Sheng Khoo
Summary: This study investigates the light induced effect of leakage current at the onset of breakdown in solar cells, finding it to be more prominent in p-type and mono c-Si cells. A proposed split-cell model offers a simple approach for handling partial shading in p-type cells, which is not captured by current breakdown models.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Engineering, Electrical & Electronic
Satadal Dutta, Raymond J. E. Hueting, Gerard J. Verbiest
Summary: In this study, we present an avalanche-mode light-emitting transistor (AMLET) in silicon, which emits light with a record low bandwidth. The AMLET achieves high optical power efficiency through a combination of a resonant cavity and carrier injection, providing new possibilities for improving the performance of silicon optical interconnects and sensors.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Chemistry, Physical
Clemens Goehler, Carsten Deibel
Summary: This Perspective focuses on the energetic CT disorder in organic solar cells and its impact on performance, including dynamic and static broadening.
ACS ENERGY LETTERS
(2022)
Article
Multidisciplinary Sciences
Behrang H. Hamadani, Margaret A. Stevens, Brianna Conrad, Matthew P. Lumb, Kenneth J. Schmieder
Summary: In this study, we used a calibrated, wide-field hyperspectral imaging instrument to investigate high growth-rate, rear-junction GaAs solar cells, and obtained absolute spectrally and spatially resolved photoluminescence images. We found a novel double-peak luminescence emission at the site of some localized defects in the active layer, with maximum peak energies corresponding to both the main band-to-band transition and a band-to-impurity optical transition below the band gap energy.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Physical
Shenghao Li, Manuel Pomaska, Andreas Lambertz, Weiyuan Duan, Karsten Bittkau, Depeng Qiu, Zhirong Yao, Martina Luysberg, Paul Steuter, Malte Koehler, Kaifu Qiu, Ruijiang Hong, Hui Shen, Friedhelm Finger, Thomas Kirchartz, Uwe Rau, Kaining Ding
Summary: In this study, TCO layers are substituted by utilizing lateral conduction of c-Si absorber in SHJ solar cells, achieving a TCO-free design with low series resistivity and good fill factor. Suppressing metal diffusion into a-Si:H layer through ozone treatment at the a-Si:H/metal interface improves passivation quality without increasing contact resistivity, enabling SHJ solar cells with TCO-free front contacts to achieve efficiencies exceeding 22%.
Article
Physics, Applied
Brianna Conrad, Behrang H. Hamadani
Summary: Hyperspectral electroluminescence and photoluminescence imaging of photovoltaic materials and devices can extract high-resolution maps of physical quantities, but require supplemental measurements for calibration. Assumptions made previously to overcome limitations may not be applicable in cases where significant spectral shape variation exists.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Sijun Luo, Lukas Trefflich, Susanne Selle, Ron Hildebrandt, Evgeny Krueger, Stefan Lange, Jingjing Yu, Chris Sturm, Michael Lorenz, Holger Von Wenckstern, Christian Hagendorf, Thomas Hoeche, Marius Grundmann
Summary: This paper reports the heteroepitaxial growth of (00.1)-oriented Zn2GeO4 thin films on c-plane sapphire substrates using pulsed laser deposition. The thin films exhibit [11.0] Zn2GeO4// [11.0] Al2O3 and [1(1) over bar.0] Zn2GeO4//[1(1) over bar.0] Al2O3 in-plane orientation relationships. The measured properties include a rocking curve full width at half maximum of 0.35 degrees, a direct bandgap of 4.9 +/- 0.1 eV, and a defect-related photoluminescence emission centered at 2.62 eV with a FWHM of 0.55 eV. This study enhances our understanding of the physical properties and potential device application of Zn2GeO4 thin films.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Tillmann Stralka, Michael Bar, Fabian Schoeppach, Susanne Selle, Chang Yang, Holger von Wenckstern, Marius Grundmann
Summary: Current probe atomic force microscopy (cp-AFM) measurements reveal the influence of the textured nature of sputtered gamma-CuI (111) thin films on charge carrier transport. The conductive behaviors of grains and grain boundaries (GBs) are differentiated and correlated, showing a clear difference between them. The time-dependent surface changes, possibly caused by atmospheric oxygen, result in the vanishing of charge carrier transport over time.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Sofie Vogt, Clemens Petersen, Max Kneiss, Daniel Splith, Thorsten Schultz, Holger von Wenckstern, Norbert Koch, Marius Grundmann
Summary: This study presents the structural and electrical properties of undoped and doped alpha-Ga2O3 thin films grown on m-plane sapphire. An undoped alpha-Ga2O3 buffer layer was introduced to improve crystal quality and stabilize the alpha-phase at lower substrate temperatures. Donor doping with tin and germanium achieved high electron mobilities. Suitable annealing temperature for ohmic Ti/Al/Au layer stacks was identified, while high annealing temperatures deteriorated the electrical properties of the thin films, indicating the need for low temperature contacting procedures for alpha-Ga2O3-based devices.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Physics, Condensed Matter
Evgeny Krueger, Volker Gottschalch, Gabriele Benndorf, Ron Hildebrandt, Ana Lucia Pereira, Michael S. Bar, Steffen Blaurock, Stefan Merker, Chris Sturm, Marius Grundmann, Harald Krautscheid
Summary: This study presents the epitaxial growth of AgxCu1-xI alloy layers and isolated small crystals on Al2O3 (0001) using the close distance sublimation (CDS) technique. Single-phase gamma-AgxCu1-xI thin films are obtained up to an Ag content of approximately 0.5, with the beta-phase also observed at higher Ag contents. The epitaxial relationships between the deposited AgxCu1-xI layers and the Al2O3 substrate, as well as the structure type, are discussed for different alloy compositions. Additionally, a method for depositing polycrystalline single-phase gamma-AgxCu1-xI thin films for Ag contents up to approximately 0.7 is presented based on the solid-state reaction of AgI layers on Al2O3 (0001) substrate with CuI. Furthermore, it is shown that the near-band-edge emission at 2 K is dominated by excitonic recombination, and the spectral position of the emission profile can be tuned by the alloy composition.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Jon Borgersen, Robert Karsthof, Vegard Ronning, Lasse Vines, Holger von Wenckstern, Marius Grundmann, Andrej Yu Kuznetsov, Klaus Magnus Johansen
Summary: Significant resistivity variations have been observed in oxides subjected to low ion doses, which cannot be explained by bulk defects. A comparative study of In2O3-based oxides revealed correlations between resistivity evolution, low ion doses, and UV illumination. The resistivity drops were attributed to oxygen desorption facilitated by irradiation/illumination, as confirmed by post-irradiation exposure to oxygen atmosphere.
Review
Materials Science, Coatings & Films
Laurenz Thyen, Daniel Splith, Max Kneiss, Marius Grundmann, Holger von Wenckstern
Summary: We introduce a new technique, MARS-PLD, for area-selective physical vapor deposition. By using a movable mask, we can selectively mask any desired area on a substrate to create multinary material composition gradients. We demonstrated the capabilities of this method by fabricating material gradients in (Mg,Zn)O thin films and on predefined two-dimensional patterns.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Nanoscience & Nanotechnology
Evgeny Krueger, Michael Seifert, Volker Gottschalch, Harald Krautscheid, Claudia S. Schnohr, Silvana Botti, Marius Grundmann, Chris Sturm
Summary: We studied the excitonic transition energy E-0 and spin-orbit split-off energy Delta(0) of gamma-AgxCu1-xI alloy thin films using reflectivity measurements at temperatures between 20 K and 290 K. The observed bowing behavior of the E-0 transition as a function of alloy composition is explained based on first-principles band structure calculations. The spin-orbit coupling increases with increasing Ag-content, and the temperature-dependent bandgap shift decreases with increasing Ag-content.
Article
Physics, Applied
Andreas Mueller, Sebastian Henn, Evgeny Krueger, Steffen Blaurock, Harald Krautscheid, Marius Grundmann, Chris Sturm
Summary: We report on the photoluminescence emission in copper iodide bulk single crystals induced by two- and three-photon absorption around 1.525eV. The non-linear optical processes were investigated through density-dependent, steady-state, and time-resolved photoluminescence spectroscopy. We observed that the photoluminescence intensity showed an almost parabolic behavior with the excitation power when the excitation energy corresponded to half of the bandgap energy. We also found a cubic contribution that increased with decreasing excitation energy. The ratio between the two- and three-photon absorption cross sections was determined to be approximately 10(-28) cm(2)s.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Condensed Matter
Marius Grundmann
Summary: This study revisits the problem of potential, electrical field, and charge density in a space charge region. Using the Boltzmann approximation, an analytical asymptotic solution is obtained. The exact solution can be found by numerically integrating an analytical function. A comparison is made with the popular abrupt (or depletion) approximation, and an analytical approximation is provided. The analytical approximation for potential, electrical field, and charge density in a space charge (depletion) region shows good agreement with the (numerically) exact solution.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Instruments & Instrumentation
Michael Lorenz, Holger Hochmuth, Holger von Wenckstern, Marius Grundmann
Summary: Pulsed laser deposition (PLD) is a highly flexible physical growth technique for thin films of functional materials. This article describes a relatively simple and reliable concept of PLD hardware that enables deposition on large areas (up to 4 inches in diameter) and tailored lateral and vertical composition spreads without the need for time-consuming hardware changes. Different PLD approaches have been implemented in various chambers by using specific and correlated computer-controlled movements of the target, substrate, and masks, along with an appropriate target phase composition.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Nanoscience & Nanotechnology
Fabian Schoeppach, Daniel Splith, Holger von Wenckstern, Marius Grundmann
Summary: In this study, metal-semiconductor field-effect transistor (MESFET) devices based on pulsed laser deposition (PLD) grown In2O3 thin films are reported. These devices exhibit on-off ratios exceeding 6 orders of magnitude and low sub-threshold swing values close to the thermodynamic limit. Oxygen plasma treatment and compensation doping with Mg are used to suppress the accumulation of electrons at the surface of In2O3, which is a major obstacle for its use as an active material in electronic devices.
ADVANCED ELECTRONIC MATERIALS
(2023)