Interfacial Behavior and Stability Analysis of p‐Type Crystalline Silicon Solar Cells Based on Hole‐Selective MoO_X/Metal Contacts

Molybdenum trioxide (MoO_X, X < 3), with a large work function, can induce upward band bending in crystalline silicon (c‐Si) when constructing a heterojunction, which makes it an attractive candidate for hole‐selective contact in c‐Si solar cells. Herein, the passivation property and hole selectivity of MoO_X thin films are investigated on p‐type c‐Si wafers using MoO_X/aluminum (Al) as rear contacts. To elevate the performance from the aspect of light management, silver (Ag) and copper (Cu) are further used as back electrodes instead of Al. Solar cells with Ag electrodes deliver the best performance with a power conversion efficiency of 18.74%, followed by Cu (17.61%) and Al (16.36%) electrodes, attributing to the better reflectivity of Ag and Cu. It is also noted that solar cells with MoO_X/Ag and MoO_X/Cu contacts show significant degradation under room temperature storage. The interfacial evolutions are then carefully studied as a function of elevated temperature that accelerate the thermodynamic process. The degradation mechanism involves redox reaction and metal diffusion at the MoO_X/metal interfaces. This work points out the importance of selecting the adjacent layers of MoO_X and regulating the interfaces to stabilize the MoO_X‐based c‐Si solar cells.