A silicon carbide-based highly transparent passivating contact for crystalline silicon solar cells approaching efficiencies of 24%

By M. Köhler, M. Pomaska, P. Prócel, R. Santbergen, Alexandr Zamchiy, B. Macco, A. Lambertz, W. Duan, Pengfei Cao, Benjamin Klingebiel and 9 more. Nature Energy, 2021

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A highly transparent passivating contact (TPC) as front contact for crystalline silicon (c-Si) solar cells could in principle combine high conductivity, excellent surface passivation and high optical transparency. However, the simultaneous optimization of these features remains challenging. Here, we present a TPC consisting of a silicon-oxide tunnel layer followed by two layers of hydrogenated nanocrystalline silicon carbide (nc-SiC:H(n)) deposited at different temperatures and a sputtered indium tin oxide (ITO) layer (c-Si(n)/SiO2/nc-SiC:H(n)/ITO). While the wide band gap of nc-SiC:H(n) ensures high optical transparency, the double layer design enables good passivation and high conductivity translating into an improved short-circuit current density (40.87 mA cm−2), fill factor (80.9%) and efficiency of 23.99 ± 0.29% (certified). Additionally, this contact avoids the need for additional hydrogenation or high-temperature postdeposition annealing steps. We investigate the passivation mechanism and working principle of the TPC and provide a loss analysis based on numerical simulations outlining pathways towards conversion efficiencies of 26%. Passivating contacts hold promise for silicon solar cells yet the simultaneous optimization of conductivity, defect passivation and optical transparency remains challenging. Now Köhler et al. devise a passivating contact based on a double layer of nanocrystalline silicon carbide that overcomes these trade-offs.

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/7ae1ab35250b0d7e4751ab41217361db39fdb8a0