Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 1: Perovskite and Photovoltaics I (joint session HL/KFM)
HL 1.3: Talk
Monday, March 17, 2025, 10:00–10:15, H13
Versatile Two-Step Process for Enhanced Stability and Efficiency in Perovskite Top Cells for Tandem Photovoltaics — •Ronja Pappenberger1,2, Roja Singh1,2, Alexander Diercks2, and Ulrich W. Paetzold1,2 — 1Institute of Microstructure Technology, KIT, Germany — 2Light Technology Institute, KIT, Germany
To achieve highly efficient 2T perovskite/silicon (Si) tandem solar cells (TSCs), textured-front Si bottom cells provide superior light-harvesting capabilities, making higher short-circuit current densities of TSC possible. A promising approach to fabricating uniform, high-quality perovskite films on these textured Si cells is the solution-based two-step method. One of the main challenges for perovskite solar cells (PSCs) remains their long-term stability. While methylammonium (MA)-based PSCs have demonstrated some of the highest efficiencies, their instability continues to pose a major obstacle. In this work, a versatile two-step process is employed – replacing MA with formamidinium – which maintains high efficiency, improves open-circuit voltage and enhances stability. A further performance boost is achieved by implementing a dual passivation strategy using PDAI2 and BAI for bulk and surface passivation. This leads to a stable power output exceeding 20.8% for Eg = 1.67 eV due to reduced non-radiative recombination at the perovskite/ETL interface and improved film crystallization, enhancing charge carrier extraction. The long-term stability is also distinctly improved. When implemented on textured Si bottom cells, this process delivers efficiencies exceeding 24% for lab-scale monolithic perovskite/Si TSCs with a 1 cm2 active area.
Keywords: perovskite solar cells; sequential deposition; dual passivation; 2T tandem solar cells; compositional engineering