Multilayer SiNx:H films as passivation and anti-reflection coating for industrial PERC solar cells

Objective: Develop high-quality multilayer SiNx:H film as anti-reflection and passivation coating for industrial PERC solar cells to improve cell efficiency. Methods: Combining OPAL2 software simulation and experimental design, high-quality multilayer SiNx:H films were realized using PECVD tool by variation of plasma and gas parameters, PERC cells were also fabricated with multilayer SiNx:H film structures to check the cell performance. Result: Simulation results showed that with the increase from double-layer to four-layer SiNx:H film, light absorption was reduced gradually, thus the light entering into the silicon bulk was increased from 95.6% to 97.5%. Corresponding experiment results showed that the short-circuit current density (Jsc) of three- and four-layer SiNx:H film were 0.11 mA/cm(2) and 0.13 mA/cm(2) higher than that of double layer SiNx:H film respectively, which was well aligned with simulation result, more current was generated due to more light reached to silicon bulk. However, the inner layer SiNx:H of double layer structure had higher refractive index (RI) with better passivation effect, resulting in higher open-circuit voltage (Voc). Finally, the experiment results showed that four-layer SiNx:H solar cells achieved 22.15% cell efficiency, which was absolutely 0.09% higher than that of double layers. The multilayer SiNx film technology can be applied directly to mass production without additional costs.