Fourteen percent efficiency ultrathin silicon solar cells with improved infrared light management enabled by hole-selective transition metal oxide full-area rear passivating contacts

The present study investigates the application of hole-selective transition metal oxide (TMO) layers (MoOx, V2Ox, and WOx) with silver (Ag) as full-area rear contact to 22.5 mu m-thick low-quality Cz p-type c-Si solar cells. Thin films of metal oxides are deposited directly on p-type c-Si by thermal evaporation at room temperature. The large work function of these TMOs creates strong accumulation at the interface with p-type c-Si, which allows only holes to transport and simultaneously suppress the interfacial recombination current density (J(0)) and contact resistivity (rho(c)). The current generation and losses of 22.5 mu m-thick solar cells with different hole-selective TMO/Ag at the rear are simulated. The presence of TMO/Ag at the rear is found to significantly reduce parasitic light absorption at longer wavelengths which becomes more pronounced for ultrathin wafers, providing significant advantages over conventional Al contact. The best device performance was attained by the MoOx/p-type c-Si solar cells, demonstrating a considerably high efficiency (eta) of 14% with V-oc of 555 mV, FF of 76.0%, and J(sc) of 33.2 mA/cm(2). Furthermore, the present work is the first to employ MoOx, V2Ox, and WOx as rear contact in ultrathin p-type c-Si solar cells.

Automated summary

The study investigated the application of hole-selective transition metal oxide layers with silver as full-area rear contact on 22.5 μm-thick low-quality Cz p-type c-Si solar cells, demonstrating that MoOx outperformed V2Ox and WOx. The TMO/Ag rear contact was found to significantly reduce parasitic light absorption at longer wavelengths and provide advantages over conventional Al contact, resulting in considerable efficiency and high device performance.