Construction of efficient silicon solar cells through polymetallic oxidation-reduction triggered by thermite reaction

Optimal metal-semiconductor contact interface is crucial for semiconductor devices, particularly for silicon solar cells aluminum-silicon contact is a key to improve the efficiency of the cell. In this work, a new type of Sb2O3-MoO3-B2O3 glass frits that can trigger a thermite reaction was utilized to improve the Al-Si interface. The low melting temperatures of these glass frits enhance the effect of thermite reaction by providing solid-liquid contact, which enables gradient distribution of the elements and leads to differences in the valence states of the Al-Si layer at the inner and surface regions. The valence states of Al and Sb at the inner layer are higher than those at the surface, while Mo is the opposite. Metallic Mo with a matched work function can lower the potential barrier, thereby improving hole selectivity and enhancing the potential skip-step. As a result, the fabricated solar cell achieved a high open-circuit voltage, a high short-circuit current, and a low series resistance. Consequently, a power conversion efficiency of 19.94% was obtained for a monocrystalline silicon solar cell with full Al-BSF. This work not only presents a new hole-selective contact for silicon solar cells, but also introduces a new approach for regulating the distribution and valence states of interface elements for enhanced efficiency.