Hydrogenation behaviors in passivated emitter and rear silicon solar cells with variously hydrogenated SiNx films

Abstract

From the point of view in sustainable energy, photovoltaic (PV) technology has been recognized as one of the most suitable solutions to replace fossil fuel technologies for electrical generation. However, in PV modules, 95% of solar cells made from P-type boron doped CZ-grown silicon substrates have a reliability issue, called light induced degradation (LID), which strongly affects their practically long-term use. Carrier induced hydrogenation (CIH) is one of the solutions through injection of excess carrier into Si solar cells with moderate thermal treatment. The mechanism of CIH process is the passivation of B-O related defects by hydrogen atoms with negative charge state. In the report, we can find the efficiency enhancement of commercial passivated emitter and rear cells (PERC) by hydrogenated silicon nitride (SiNx:H) films which were prepared by plasma-enhanced chemical vapor deposition and released hydrogen for Si passivation. In order to understand the behaviors of hydrogenation in Si solar cells, we manipulate the amount of hydrogen effused from the rear SiNx:H layers into the silicon substrate. A quadratic trend of average conversion efficiency gain for solar cells was observed after CIH treatment process. The mechanism of hydrogenation for PERC, including carrier induced hydrogenation and excess-hydrogen induced degradation, was investigated.