Jonas Schön received the PhD degree in 2011 from the University of Constance. Since 2016, he has been working at the University of Freiburg in the field of silicon-perovskite and III-V multijunction solar cell modelling.
Simulation-based structure optimization of monolithic Perovskite/Perovskite/Silicon triple junction solar cells
Perovskite-based triple-junction solar cells have the potential for highly efficient and cost-effective photovoltaic energy conversion [1]. However, the increased number of material layers and, thus increased complexity requires a target-oriented optimization of the structure and careful selection of materials. Simulations assist in identifying factors that contribute to efficiency loss, thereby guiding developers to improve specific layers. Current key challenges include achieving stable perovskite compositions with the right bandgap, as well as identifying hole and electron extraction layers with good passivation quality and suitable band alignment. We have developed a comprehensive opto-electrical model for the perovskite/perovskite/silicon structure using Sentaurus TCAD. The model has been validated through measurements on both triple-junction [2,3] and single-junction solar cells. Single-junction perovskite solar cells were fabricated and characterized to distinguish between optical and electrical losses in the two subcells. The talk will outline a developmental roadmap for monolithic perovskite/perovskite/silicon triple-junction cells and show the first technological steps. A first improvement involves adjusting the thicknesses of the perovskite layers to achieve current matching in the top subcells [3]. Furthermore, using perovskites with optimized bandgaps could significantly enhance the photocurrent density. We demonstrate that implementing a fully textured structure, a practical efficiency of 44.3% for this kind of triple-junction technology can be achieved. In line with the characterization of Perovskite/Silicon dual-junction solar cells [4], we have identified selectivity and recombination at the ETL/HTL interfaces in both perovskite cells as the primary sources of electrical losses.
