TY - JOUR A1 - Mero, M. A1 - Clapp, B. A1 - Jasapara, J.C. A1 - Rudolph, W. A1 - Ristau, D. A1 - Starke, K. A1 - Krüger, Jörg A1 - Martin, Sven A1 - Kautek, Wolfgang T1 - On the damage behavior of dielectric films when illuminated with multiple femtosecond laser pulses N2 - The physical effects reducing the damage threshold of dielectric films when exposed to multiple femtosecond pulses are investigated. The measured temperature increase of a Ta2O5 film scales exponentially with the pulse fluence. A polarized luminescence signal is observed that depends quadratically on the pulse fluence and is attributed to twophoton excitation of self-trapped excitons that form after band-to-band excitation. The damage fluence decreases with increasing pulse number, but is independent of the repetition rate from 1 Hz to 1 kHz at a constant pulse number. The repetition rate dependence of the breakdown threshold is also measured for TiO2 , HfO2, Al2O3, and SiO2 films. A theoretical model is presented that explains these findings. KW - Laser-induced damage KW - Laser materials KW - Ultrafast phenomena KW - Coatings PY - 2005 DO - https://doi.org/10.1117/1.1905343 SN - 0892-354X VL - 44 IS - 5 SP - 051107-1-051107-7 PB - Dekker CY - New York, NY AN - OPUS4-7406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Berger, J. A1 - Zahedi-Azad, S. A1 - Voss, H. A1 - Ernst, O.C. A1 - Hammerschmidt, R. A1 - Boeck, T. A1 - Martin, J. A1 - Bonse, J. A1 - Krüger, J. A1 - Schmid, M. T1 - CuInSe2-based micro-concentrator solar cells fabricated from In islands grown by laser-assisted MO-CVD N2 - Micro-concentrator solar cells offer a promising route for reducing material usage in photovoltaics. For Cu(In,Ga)Se2, multiple micro-concentrator manufacturing methods have already been evaluated. All of them involve either high preparation complexity or post-processing to recycle unused precursor or absorber materials. In this work, a new method using laser-assisted metal-organic chemical vapor deposition (LA-MOCVD) was applied to directly grow arrays of indium micro-islands. These arrays are examined and further processed to CuInSe2 micro-solar cell arrays. The geometry and morphology of the islands were investigated and compared before and after absorber formation. The investigation shows that the absorber growth is limited to the vertical direction normal to the substrate surface and that the starting morphology is preserved. Furthermore, the absorber island arrays are processed into micro-modules and operational solar cells are achieved as a proof of principle. These not yet optimized arrays reach a conversion efficiency of 0.65% under 1 sun illumination. Under 17 suns of light concentration, the efficiency gain is between 60 and 250%. This work demonstrates the method's viability for the fabrication of micro-solar cell arrays, with clear potential for achieving higher conversion efficiencies through future optimization. KW - Micro-concentrator solar cells KW - Laser-assisted chemical vapor deposition KW - CISe KW - Bottom-up fabrication KW - Resource efficiency PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656711 DO - https://doi.org/10.1016/j.solmat.2026.114284 SN - 0927-0248 VL - 301 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-65671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kim, Y.S. A1 - Li, Y.-C. A1 - Pitts, W.M. A1 - Werrel, Martin A1 - Davis, R.D. T1 - Rapid growing clay coatings to reduce the fire threat of furniture N2 - Layer-by-layer (LbL) assembly coatings reduce the flammability of textiles and polyurethane foam but require extensive repetitive processing steps to produce the desired coating thickness and nanoparticle fire retardant content that translates into a fire retardant coating. Reported here is a new hybrid bi-layer (BL) approach to fabricate fire retardant coatings on polyurethane foam. Utilizing hydrogen bonding and electrostatic attraction along with the pH adjustment, a fast growing coating with significant fire retardant clay content was achieved. This hybrid BL coating exhibits significant fire performance improvement in both bench scale and real scale tests. Cone calorimetry bench scale tests show a 42% and 71% reduction in peak and average heat release rates, respectively. Real scale furniture mockups constructed using the hybrid LbL coating reduced the peak and average heat release rates by 53% and 63%, respectively. This is the first time that the fire safety in a real scale test has been reported for any LbL technology. This hybrid LbL coating is the fastest approach to develop an effective fire retardant coating for polyurethane foam. KW - Layer-by-layer assembly KW - Polyurethane foam KW - Sodium montmorillonite KW - Flame retardant KW - Real scale mockup PY - 2014 DO - https://doi.org/10.1021/am405259n SN - 1944-8244 SN - 0013-936X SN - 1944-8252 VL - 6 IS - 3 SP - 2146 EP - 2152 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-31489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - B, Yang A1 - Chua, Y. Z. A1 - Szymoniak, Paulina A1 - Carta, M A1 - Malpass-Evans, R A1 - McKeown, N A1 - Harrison, W A1 - Budd, P A1 - Schick, C A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Effect of backbone rigidity on the glass transition of polymers of in-trinsic microporosity probed by fast scanning calorimetry N2 - Polymers of Intrinsic Microporosity (PIMs) of high performance have developed as materials with a wide application range in gas separation and other energy-related fields. Further optimization and long-term behavior of devices with PIMs require an understanding of the structure-property relationships including physical aging. In this context the glass transi-tion plays a central role, but with conventional thermal analysis a glass transition is usually not detectable for PIMs be-fore their thermal decomposition. Fast scanning calorimetry provides evidence of the glass transition for a series of PIMs, as the time scales responsible for thermal degradation and for the glass transition are decoupled by employing ultrafast heating rates of tens of thousands K s-1. The investigated PIMs were chosen considering the chain rigidity. The estimated glass transition temperatures follow the order of the rigidity of the backbone of the PIMs. KW - Polymers of intrinsic microporosity KW - Fast scanning calormetry PY - 2019 DO - https://doi.org/10.1021/acsmacrolett.9b00482 SN - 2161-1653 VL - 8 IS - 8 SP - 1022 EP - 1028 PB - ACS Publications AN - OPUS4-48617 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -