Titanium Silicide: A Promising Candidate of Recombination Layer for Perovskite/Tunnel Oxide Passivated Contact Silicon Two-Terminal Tandem Solar Cells.

This study proposes a titanium silicide (TiSi) recombination layer for perovskite/tunnel oxide passivated contact (TOPCon) 2-T tandem solar cells as an alternative to conventional transparent conductive oxide (TCO)-based recombination layers. TiSi was formed while TiO was made by oxidizing a Ti film deposited on the p-Si layer. The reaction formation mechanism was proposed based on the diffusion theory supported by experimental results. The optical and electrical properties of the TiSi layer were optimized by controlling the initial Ti thicknesses (5-100 nm). With the initial Ti of 50 nm, the lowest reflectance and highly ohmic contact between the TiO and p-Si layers with a contact resistivity of 161.48 mΩ·cm were obtained. In contrast, the TCO interlayer shows Schottky behavior with much higher contact resistivities. As the recombination layer of TiSi and the electron transport layer of TiO are formed simultaneously, the process steps become simpler. Finally, the MAPbI/TOPCon tandem device yielded an efficiency of 16.23%, marking the first reported efficiency for a device including a silicide-based interlayer.