Roland Scheer
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Assessment of transparent conductive oxides as back contacts for inline-fabricated Cu(In,Ga)Se<sub>2</sub> solar cells Open
The integration of transparent back contacts (TBCs) into Cu(In,Ga)Se 2 (CIGS) and (Ag,Cu)(In,Ga)Se 2 thin-film solar cells presents significant opportunities for enhancing device performance and enabling applications such as bifacial and t…
Effect of top cell absorber thickness and bifacial illumination on monolithic (Ag,Cu)(In,Ga)Se<sub>2</sub>/Si tandem solar cells Open
Wide bandgap (Ag,Cu)(In,Ga)Se 2 (ACIGSe) is a viable candidate as top cell absorber in tandem devices. In this work, we investigate monolithic two-terminal ACIGSe-Si tandem cells with a bandgap of 1.5 eV. Our research focuses on the direct…
Ultrathin Cu(In,Ga)Se<sub>2</sub> solar cells: enhanced absorption by nanotextured functional back contacts Open
Ultrathin Cu(In,Ga)Se 2 solar cell conversion efficiencies are limited by incomplete absorption of the solar spectrum. In this study, we experimentally investigate a light management strategy to enhance the performance of ultrathin Cu(In,G…
Structural analyses and photovoltaic device simulations in two and three dimensions applied to Ag-alloyed Cu(In,Ga)Se<sub>2</sub> solar cells Open
The present study reports on the structural changes and related photovoltaic properties resulting from the addition of Ag in Cu(In,Ga)Se 2 (CIGS)-based thin-film solar cells analysed using two-dimensional (2D) and three-dimensional (3D) an…
Recombination Effects of Urbach Tails as Trap States in Cu(In, Ga)Se<sub>2</sub> Solar Cells Probed by Temperature‐Dependent Junction‐Transient Spectroscopies Open
Recombination centers such as carrier traps due to point defects have long been known as one major limitation to the device efficiency of solar cells. Realizing the origin and the mechanism of the trapping and recombination processes enabl…
Ordered Vacancy Compound Formation at the Interface of Cu(In,Ga)Se<sub>2</sub> Absorber with Sputtered In<sub>2</sub>S<sub>3</sub>‐Based Buffers: An Atomic‐Scale Perspective Open
The design of a Cd‐free and wider‐bandgap buffer layer is stringent for future Cu(In,Ga)Se 2 (CIGSe) thin‐film solar cell applications. For that, an In 2 S 3 buffer layer alloyed with a limited amount of O (well below 25 mol%) has been pro…
Economic Consequences Based on Reversible and Irreversible Degradation of PV Park in the Harsh Climate Conditions of Iraq Open
Photovoltaic (PV) system reliability and durability investigations are essential for industrial maturity and economic success. Recently, PV systems received much interest in Iraq due to many reasons—for instance, power shortage, global war…
Analysis and prediction of the performance and reliability of PV modules installed in harsh climates: Case study Iraq Open
The increasing global demand for renewable energy necessitates a comprehensive understanding of solar photovoltaic (PV) system performance and reliability, particularly in harsh climates such as Iraq. Despite ambitious targets to diversify…
Structural Evolution of Sequentially Evaporated (Cs,FA)Pb(I,Br)<sub>3</sub> Perovskite Thin Films via In Situ X‐Ray Diffraction Open
Evaporation of perovskite thin films for solar cell applications is a solvent‐free, well controllable, and scalable deposition path with promising prospects for commercialization. Compared to commonly applied simultaneous co‐evaporation of…
Sodium in Cu(In, Ga)Se<sub>2</sub> Solar Cells: To Be or Not to Be Beneficial Open
In this work, the dual effect of Na in the copper indium gallium diselenide (CIGS) absorber is studied. Na doping exhibits a drastic improvement of the cell efficiency mainly by an increase in the open‐circuit current and fill factor. Howe…
Elucidating the local structure of V substitutes in In<sub>2</sub>S<sub>3</sub> as potential intermediate band material by x-ray absorption spectroscopy and first principles calculations Open
Vanadium doped indium sulphide, In 2 S 3 :V, is studied as a potential absorber material for intermediate band (IB) solar cells. Based on electronic considerations, it is usually assumed that V occupies octahedrally coordinated In sites, a…
Effect of charge selective contacts on the quasi Fermi level splitting of CuGa<sub>3</sub>Se<sub>5</sub> thin film photocathodes for hydrogen evolution and methylviologen reduction Open
The defect-copper chalcopyrite CuGa 3 Se 5 is a promising photocathode material for solar hydrogen generation. Here we assess its performance with photoelectrochemical measurements and vibrating Kelvin probe surface photovoltage spectrosco…
Impact of dynamic co-evaporation schemes on the growth of methylammonium lead iodide absorbers for inverted solar cells Open
A variety of different synthesis methods for the fabrication of solar cell absorbers based on the lead halide perovskite methylammonium lead iodide (MAPbI 3 , MAPI) have been successfully developed in the past. In this work, we elaborate u…
Characterization of the Stability of Indium Tin Oxide and Functional Layers for Semitransparent Back‐Contact Applications on Cu(in,Ga)Se<sub>2</sub>Solar Cells Open
Herein, a detailed study of the stability of different ITO‐based back‐contact configurations (including bare ITO contacts and contacts functionalized with nanometric Mo, MoSe 2 , and MoS 2 layers) under the coevaporation processes develope…
Stoichiometry dependent phase evolution of co-evaporated formamidinium and cesium lead halide thin films Open
Ensuring single-phase growth during evaporation of perovskite absorbers for solar cells is a critical step towards industrialization, since the mechanisms of δ-phase suppression need to be fully understood.
Comparison of Mo and ITO back contacts in CIGSe solar cells: Vanishing of the main capacitance step Open
Admittance measurements of Cu (In, Ga)Se 2 (CIGSe) solar cells typically show at least one capacitance step, the so‐called N1 signal. Its origin is still under debate, even though the signal is present in almost all CIGSe solar cells. In t…
Dominant recombination path in low-bandgap kesterite CZTSe(S) solar cells from red light induced metastability Open
Hetero-junction kesterite Cu2ZnSn(S,Se)4 solar cells with low bandgap obtained from three different methods of fabrication were exposed to red light illumination, and the changes observed in their electronic properties due to this exposure…
View article: Influence of the Rear Interface on Composition and Photoluminescence Yield of CZTSSe Absorbers: A Case for an Al<sub>2</sub>O<sub>3</sub> Intermediate Layer
Influence of the Rear Interface on Composition and Photoluminescence Yield of CZTSSe Absorbers: A Case for an Al<sub>2</sub>O<sub>3</sub> Intermediate Layer Open
The rear interface of kesterite absorbers with Mo back contact represents one of the possible sources of nonradiative voltage losses (ΔVoc,nrad) because of the reported decomposition reactions, an uncontrolled growth of MoSe2, or a nonopti…
Microscopic origins of performance losses in highly efficient Cu(In,Ga)Se2 thin-film solar cells Open
Thin-film solar cells based on polycrystalline absorbers have reached very high conversion efficiencies of up to 23-25%. In order to elucidate the limiting factors that need to be overcome for even higher efficiency levels, it is essential…
Effect of Na‐PDT and KF‐PDT on the photovoltaic performance of wide bandgap Cu (In,Ga)Se2 solar cells Open
Cu (In,Ga)Se 2 solar cells exhibit higher efficiencies if an appropriate Ga gradient is introduced and if the absorber is doped with sodium (Na) plus a heavier alkali atom such as potassium. However, a Gallium gradient in the presence of N…
Ultrathin CIGSe Solar Cells with Integrated Structured Back Reflector Open
To reduce the thickness of CuIn 1‐ x Ga x Se 2 (CIGSe) solar cells, light management concepts must be used. One concept is the combination of an Al/indium1‐tin1‐oxide (ITO) reflector/contact and an optical scattering element at the back si…
The electrical and optical properties of kesterites Open
Kesterite Cu 2 ZnSn(S x Se 1- x ) 4 (CZTSSe) semiconductor materials have been extensively studied over the past decade, however despite significant efforts, the open circuit voltage remains below 60% of the theoretical maximum. Understand…
Ternary and Multinary Compounds (20th ICTMC) Open
The 20th International Conference on Ternary and Multinary Compounds (ICTMC-20) was held on 5-9 September 2016 at the Leopoldina, Halle (Saale), Germany and was organized by members of the Martin-Luther-University in Halle. Scientifically,…