Stable Molybdenum Nitride Contact for Efficient Silicon Solar Cells

Abstract

Carrier‐selective passivating contacts play a crucial role in highly efficient silicon solar cells targeting the cost‐effective photovoltaic industry. Widely developed hole‐selective passivating‐contact molybdenum oxide (MoOx) exhibits inferior long‐term stability induced by chemical reactions between the MoOx and the adjacent metals. Herein, low‐temperature magnetron‐sputtering‐deposited molybdenum nitride (MoNx) films are developed as stable hole‐selective passivating contacts for crystal silicon solar cells. The work function of the MoNx films can be as deep as 5.62 eV featuring a low resistivity of 5.0 × 10−4 Ω cm by optimizing the deposition process. Quasi‐metallic MoNx integrated with a MoOx passivating layer is verified to act as effective hole‐selective passivating contacts for crystal silicon solar cells, yielding a power convertion efficiency (PCE) above 17%. Although the hole‐selective passivation of MoNx films is inferior to fresh MoOx ones, the device performance with MoNx film is kept stable with time in air exposure and surpasses MoOx films after 6 months. The stable performance is ascribed to the metal electrodes diffusion barrier and insusceptible work function of MoNx films compared to MoOx films. This work makes a preliminary exploration to develop efficient crystal silicon solar cells with stable and cost‐effective metal nitrides as hole‐selective passivating contacts.