Revealing Surface and Interface Evolution of Molybdenum Nitride as Carrier-Selective Contacts for Crystalline Silicon Solar Cells

• Published in: ACS applied materials & interfaces 2023-03, Vol.15 (10), p.13753-13760
• Main Authors: Li, Yajuan, Li, Yuxiong, Heger, Julian E., Zhou, Jungui, Guan, Tianfu, Everett, Christopher R., Wei, Wei, Hong, Zhiwei, Wu, Yanfei, Jiang, Xinyu, Yin, Shanshan, Yang, Xinbo, Li, Dongdong, Jiang, Chunping, Sun, Baoquan, Müller-Buschbaum, Peter
• Format: Article
• Language: English
• Subjects: air; crystal structure; evolution; molybdenum; nitrides; silicon; spectroscopy; Surfaces, Interfaces, and Applications; X-radiation
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.2c22781

Molybdenum nitride (MoN x ) was perceived as carrier-selective contacts (CSCs) for crystalline silicon (c-Si) solar cells due to having proper work functions and excellent conductivities. However, the poor passivation and non-Ohmic contact at the c-Si/MoN x interface endow an inferior hole selectivity. Here, the surface, interface, and bulk structures of MoN x films are systematically investigated by X-ray scattering, surface spectroscopy, and electron microscope analysis to reveal the carrier-selective features. Surface layers with the composition of MoO2.51N0.21 form upon air exposure, which induces the overestimated work function and explains the origin of inferior hole selectivities. The c-Si/MoN x interface is confirmed to adopt long-term stability, providing guidance for designing stable CSCs. A detailed evolution of the scattering length density, domain sizes, and crystallinity in the bulk phase is presented to elucidate its superior conductivity. These multiscale structural investigations offer a clear structure–function correlation of MoN x films, providing key inspiration for developing excellent CSCs for c-Si solar cells.