TY - JOUR A1 - Schultz, Christof A1 - Fenske, Markus A1 - Dion-Bertrand, Laura-Isabelle A1 - Gélinas, Guillaume A1 - Marcet, Stéphane A1 - Dagar, Janardan A1 - Bartelt, Andreas A1 - Schlatmann, Rutger A1 - Unger, Eva A1 - Stegemann, Bert T1 - Hyperspectral Photoluminescence Imaging for Spatially Resolved Determination of Electrical Parameters of Laser‐Patterned Perovskite Solar Cells JF - Solar RRL N2 - Absolute calibrated hyperspectral photoluminescence (PL) imaging is utilized to access, in a simple and fast way, the spatial distribution of relevant solar cell parameters such as quasi‐Fermi level splitting, optical diode factor, Urbach energies Eu, and shunt resistances Rsh, without the need for electrical measurements. Since these metrics play a significant role in evaluating the process windows for electrical series interconnection by laser patterning, this approach is followed to systematically locate and quantify electrical losses that may occur as a result of the laser‐patterning process for monolithic series interconnection. It is shown that both picosecond and nanosecond laser pulses can be used for successful series interconnection. In both cases, only minor lateral material alterations occur, localized in a few μm wide region adjacent to the edges of the scribe lines. Furthermore, the acquisition and analysis of these hyperspectral PL datasets provide insights in the material removal process, from which it is concluded that the perovskite is rather resilient against the thermal impact of the laser. KW - Laserablation KW - ablation KW - hyperspectral photoluminescence KW - lasers KW - perovskites KW - photovoltaics KW - solar modules KW - thin films KW - Laser KW - Perowskitgruppe KW - Fotovoltaik Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:523-18215 SN - 2367-198X VL - 7 IS - 22 PB - Wiley ER - TY - JOUR A1 - Fenske, Markus A1 - Schultz, Christof A1 - Dagar, Janardan A1 - Kosasih, Felix Utama A1 - Zeiser, Andreas A1 - Junghans, Cornelia A1 - Bartelt, Andreas A1 - Ducati, Caterina A1 - Schlatmann, Rutger A1 - Unger, Eva A1 - Stegemann, Bert T1 - Improved Electrical Performance of Perovskite Photovoltaic Mini‐Modules through Controlled PbI2 Formation Using Nanosecond Laser Pulses for P3 Patterning JF - Energy Technology N2 - The upscaling of perovskite solar cells to modules requires the patterning of the layer stack in individual cells that are monolithically interconnected in series. This interconnection scheme is composed of three lines, P1–P3, which are scribed using a pulsed laser beam. The P3 scribe is intended to isolate the back contact layer of neighboring cells, but is often affected by undesired effects such as back contact delamination, flaking, and poor electrical isolation. Herein, the influence of the laser pulse duration on the electrical and compositional properties of P3 scribe lines is investigated. The results show that both nanosecond and picosecond laser pulses are suitable for P3 patterning, with the nanosecond pulses leading to a higher open circuit voltage, a higher fill factor, and a higher power conversion efficiency. It is found that the longer pulse duration resultes in a larger amount of PbI2 formed within the P3 line and a thin Br‐rich interfacial layer which both effectively passivate defects at the scribe line edges and block charge carrier in its vicinity. Thus, nanosecond laser pulses are preferable for P3 patterning as they promote the formation of beneficial chemical phases, resulting in an improved photovoltaic performance. KW - Laserablation KW - ablation KW - laser KW - perovskites KW - photovoltaics KW - series interconnections KW - solar modules KW - thin films KW - Laser KW - Perowskit KW - Fotovoltaik Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:523-15841 VL - 9 IS - 4 SP - 1 EP - 8 ER - TY - JOUR A1 - Dagar, Janardan A1 - Paramasivam, Gopinath A1 - Klimm, Carola A1 - Fenske, Markus A1 - Schultz, Christof A1 - Schlatmann, Rutger A1 - Stegemann, Bert A1 - Unger, Eva T1 - Stability Assessment of p-i-n Perovskite Photovoltaic Mini-Modules Utilizing Different Top Metal Electrodes JF - Micromachines N2 - Long-term stability is one of the major challenges for p-i-n type perovskite solar modules (PSMs). Here, we demonstrate the fabrication of fully laser-patterned series interconnected p-i-n perovskite mini-modules, in which either single Cu or Ag layers are compared with Cu/Au metalbilayer top electrodes. According to the scanning electron microscopy measurements, we found that Cu or Ag top electrodes often exhibit flaking of the metal upon P3 (top contact removal) laser patterning. For Cu/Au bilayer top electrodes, metal flaking may cause intermittent short-circuits between interconnected sub-cells during operation, resulting in fluctuations in the maximum power point (MPP). Here, we demonstrate Cu/Au metal-bilayer-based PSMs with an efficiency of 18.9% on an active area of 2.2 cm2 under continuous 1-sun illumination. This work highlights the importance of optimizing the top-contact composition to tackle the operational stability of mini-modules, and could help to improve the feasibility of large-area module deployment for the commercialization of perovskite photovoltaics. KW - self-assembled monolayer KW - module KW - electrode KW - perovskite KW - maximum power point KW - flakes KW - stability Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:523-14784 SN - 2072-666X VL - 12 IS - 4 PB - MDPI ER - TY - JOUR A1 - Li, Jinzhao A1 - Dagar, Janardan A1 - Shargaieva, Oleksandra A1 - Flatken, Marion A. A1 - Köbler, Hans A1 - Fenske, Markus A1 - Schultz, Christof A1 - Stegemann, Bert A1 - Just, Justus A1 - Többens, Daniel M. A1 - Abate, Antonio A1 - Munir, Rahim A1 - Unger, Eva T1 - 20.8% Slot‐Die Coated MAPbI3 Perovskite Solar Cells by Optimal DMSO‐Content and Age of 2‐ME Based Precursor Inks JF - Advanced Energy Materials N2 - Solar cells incorporating metal‐halide perovskite (MHP) semiconductors are continuing to break efficiency records for solution‐processed solar cell devices. Scaling MHP‐based devices to larger area prototypes requires the development and optimization of scalable process technology and ink formulations that enable reproducible coating results. It is demonstrated that the power conversion efficiency (PCE) of small‐area methylammonium lead iodide (MAPbI3) devices, slot‐die coated from a 2‐methoxy‐ethanol (2‐ME) based ink with dimethyl‐sulfoxide (DMSO) used as an additive depends on the amount of DMSO and age of the ink formulation. When adding 12 mol% of DMSO, small‐area devices of high performance (20.8%) are achieved. The effect of DMSO content and age on the thin film morphology and device performance through in situ X‐ray diffraction and small‐angle X‐ray scattering experiments is rationalized. Adding a limited amount of DMSO prevents the formation of a crystalline intermediate phase related to MAPbI3 and 2‐ME (MAPbI3‐2‐ME) and induces the formation of the MAPbI3 perovskite phase. Higher DMSO content leads to the precipitation of the (DMSO)2MA2Pb3I8 intermediate phase that negatively affects the thin‐film morphology. These results demonstrate that rational insights into the ink composition and process control are critical to enable reproducible large‐scale manufacturing of MHP‐based devices for commercial applications. KW - ink age KW - perovskite solar cells KW - slot‐die coating KW - SAXS, WAXS Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:523-14864 VL - 11 IS - 10 PB - Wiley ER - TY - GEN A1 - Stegemann, Bert A1 - Deutscher, Tobias T1 - Classroom Response Systems (Clicker) - Vorlesungen á la "Wer wird Millionär"? N2 - Umsetzung eines interaktiven Lehrkonzepts unter Verwendung eines Classroom Response Systems KW - Studienvorbereitung KW - Studienbegleitung KW - Weiterbildung KW - Classroom Response Systems KW - CRS Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:523-1620 SP - 1 EP - 1 ER - TY - JOUR A1 - Schultz, Christof A1 - Fenske, Markus A1 - Otto, Nicolas A1 - Dion-Bertrand, Laura-Isabelle A1 - Gélinas, Guillaume A1 - Marcet, Stéphane A1 - Dagar, Janardan A1 - Schlatmann, Rutger A1 - Unger, Eva A1 - Stegemann, Bert ED - Bouclé, Johann T1 - Loss Analysis of P3 Laser Patterning of Perovskite Solar Cells via Hyperspectral Photoluminescence Imaging JF - Solar N2 - Upscaling perovskite solar cells and modules requires precise laser patterning for series interconnection and spatial characterization of cell parameters to understand laser–material interactions and their impact on performance. This study investigates the use of nanosecond (ns) and picosecond (ps) laser pulses at varying fluences for the P3 patterning step of perovskite solar cells. Hyperspectral photoluminescence (PL) imaging was employed to map key parameters such as optical bandgap energy, Urbach energy, and shunt resistance. The mappings were correlated with electrical measurements, revealing that both ns and ps lasers can be utilized for effective series interconnections with minimal performance losses at optimized fluences. Our findings provide a deeper understanding of fluence-dependent effects in P3 patterning. Moreover, the results demonstrate that the process window is robust, allowing for reasonable cell performance even with deviations from optimal parameters. This robustness, coupled with the scalability of the laser patterning process, emphasize its suitability for industrial module production. KW - Photoluminescence KW - photoluminescence KW - perovskite KW - laser KW - ablation KW - photovoltaic KW - series interconnection KW - solar module KW - thin film KW - hyperspectral KW - Perovskite KW - Laser KW - Photovoltaic Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:523-20545 SN - 2673-9941 VL - 5 IS - 2 PB - MDPI ER -