Perovskite/homojunction-silicon tandem solar cells with optimized silicon nitride passivation and advanced double-sided ohmic contacts

Abstract

Perovskite/silicon tandem (PST) cells, especially those utilizing heterojunction silicon cells, have made remarkable progress in achieving high efficiency. However, homojunction silicon-based technologies still dominate the photovoltaic (PV) market due to their economic viability and easy fabrication processes. In this work, we present an optimized optical and electrical design for homojunction silicon-based perovskite tandem cells, introducing a refractive-index-matched silicon nitride (SiNx) passivation layer with double-sided ohmic contacts. Using the transfer length method, the Cr/Ag/Sn metal was identified as the optimal choice, offering superior ohmic characteristics when interfacing with both the indium tin oxide recombination layer and the silicon emitter. This innovative double-sided ohmic contact, which locally penetrates through the refractive-index-matched SiNx layer, not only establishes robust electrical connectivity between the top and bottom sub cells but also significantly reduces interfacial reflection losses. As a result, the monolithic PST cell achieves enhanced PV performance, with a short-circuit current density of 16.48 mA/cm2, open-circuit voltage of 1.75 V, and a power conversion efficiency of 23.11 %.