Low-temperature PECVD silicon-nitride passivation for perovskite solar cell

Low temperature PECVD Si-nitride was investigated as passivation layer for Ag electrode of perovskite solar cell, which is highly sensitive to H2O. FTIR analysis verified that, with H2O in aging ambient, hydrolysis and oxidation reaction occurred on Si-nitride films, which weakened and cracked Si-nitride film. Adding O2 in aging ambients, surface Si-N bonds could be passivated by adsorbed O and hydrolysis reaction of Si-nitride could be reduced. It is confirmed by FTIR spectrum of aged Si-nitirde films in O2/N2/H2O ambient. With further increasing O2 partial pressure (over 25% O2) in O2/N2/H2O ambient, surface-adsorbed O diffused into Si-nitride and accumulated at Si-nitride/Ag interface, which built-up pressure and cracking Si-nitride film. Thus, it is concluded that the pressure built-up from O2 accumulation and hydrolysis and oxidation reactions of Si-nitride are key factors for the reliability of Si-nitride passivation films.