Surface modification of sputtered NiO<sub>x</sub> hole transport layer for CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> perovskite solar cells
Masatoshi Yanagida, T. Nakamura, Tsukasa Yoshida, Dhruba B. Khadka, Yasuhiro Shirai, Kenjiro Miyano
Abstract
Abstract The modification of the sputtered NiO x ( x ≧ 1)/CH 3 NH 3 PbI 3 interface by 2-(3,6-dimethoxy-9H-carbazol-9-yl) ethyl] phosphonic acid (MeO-2PACz) considerably enhances the power conversion efficiency of perovskite solar cells whose structure is ITO/NiO x /CH 3 NH 3 PbI 3 /[6,6]-phenyl C 61 butyric acid methyl ester (PCBM)/aluminum-doped zinc oxide (AZO)/Ag. In devices without MeO-2PACz, the internal quantum efficiency (IQE) above 450 nm increases with the increase in NiO x thickness from 4 to 53 nm, although even in the thickest case, the IQE never reaches 90%. On the other hand, devices with MeO-2PACz modified NiO x show thickness-insensitive IQE of ca. 90%. We propose that (1) MeO-2PACz effectively fills the pinholes in thinner NiO x and (2) it passivates the carrier trapping/recombination defects at the NiO x /perovskite interface.