Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 4: Perovskite and Photovoltaics I (joint session HL/KFM)
HL 4.1: Talk
Monday, March 18, 2024, 09:30–09:45, EW 203
Improving Performance of Two-Step Processed Perovskite Top Cells for Tandem Photovoltaic Applications — •Ronja Pappenberger1,2, Alexander Diercks2, Julian Petry1,2, Paul Fassl1,2, and Ulrich W. Paetzold1,2 — 1Institute of Microstructure Technology, KIT, Germany — 2Light Technology Institute, KIT, Germany
For high-performance application of perovskite solar cells (PSCs) in monolithic perovskite/silicon tandem configuration, an optimal bandgap and process method of the perovskite top cell is required. While the two-step method leads to regular perovskite film crystallization, engineering wider bandgaps (Eg > 1.65 eV) for the solution-based two-step method remains a challenge. This work introduces an effective and facile strategy to increase the bandgap of two-step solution-processed perovskite films by incorporating bromide in both deposition steps, the inorganic (step 1, PbBr2) and the organic (step 2, FABr) precursor deposition. This strategy yields improved charge carrier extraction and quasi-Fermi level splitting with PCEs up to 15.9%. Further improvements are achieved by introducing CsI in the bulk and utilizing LiF as surface passivation, resulting in a stable power output exceeding 18.9% for Eg = 1.68 eV. This additional performance boost arises from enhanced perovskite film crystallization, leading to improved charge carrier extraction. Laboratory scale planar monolithic perovskite/silicon tandem solar cells (TSCs) (1 cm2 active area) achieve PCEs up to 25.7%. In addition, research is being conducted into implementation on textured monolithic perovskite/silicon TSCs.
Keywords: perovskite solar cells; sequential deposition; bandgap engineering; 2T tandem solar cells