Ingvild Bergsbak

• Bergsbak, Ingvild; Nordseth, Ørnulf; Saxegaard, Kjetil Karlsen; Olsen, Vegard Skiftestad; Wenckstern, Holger Von & Bergum, Kristin (2024). Device Simulation of 25.9% Efficient ZnOxNy/Si Tandem Solar Cell. Advanced Theory and Simulations. 7(12). doi: 10.1002/adts.202400252. Full text in Research Archive Show summary

  The novel, high electron mobility material ZnOxNy has been investigated theoretically as an absorber in a two-terminal tandem solar cell. In addition to its high mobility, ZnOxNy can attain sufficiently low carrier concentration to enable pn-junctions, and has a tunable bandgap around the 1.7 eV range. It is therefore suitable for pairing with a Si-based bottom cell. In addition to the ZnOxNy layer, the tandem cell consists of a Cu2O emitter and a Si heterojunction bottom cell. A buffer layer is introduced between the emitter and absorber in the top cell to mediate a large valence band offset that resulted in a poor fill factor, FF. A ZnOxNy buffer layer bandgap of 1.5 eV gave the highest power conversion efficiency (PCE). The objective is to estimate the optimal performance of ZnOxNy in a tandem solar cell. The dependence of current–voltage (J–V) characteristics on thickness, mobility and carrier concentration in the ZnOxNy layer is evaluated, and found to yield maximum performance with 0.35 𝛍m, 250 cm2 Vs–1 and 1016 cm−3, respectively. Using these conditions, the J–V parameters of the device under AM1.5 illumination are short circuit current density, JSC = 17.76 mA cm−2, open circuit voltage, VOC = 1.74 V, FF = 83.8% and PCE = 25.9%. With this, it is reported on, to the best of the knowledge, the first device simulation based on ZnOxNy.

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• Bergsbak, Ingvild (2024). Heat Treatment of SnWO4 Films Grown with PLD. Full text in Research Archive

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