Performance enhancement of perovskite solar cells by doping TiO2 blocking layer with group VB elements

Abstract Hole blocking layer with pinhole-free and excellent electron conductivity is critical in high-efficient perovskite solar cells. In this paper, we investigated thoroughly the effect of tantalum (Ta) or niobium (Nb) dopant in TiO 2 compact layer. Both Ta and Nb dopants could enhance the electron conductivity of TiO 2 compact film without declining their light transmittance property. The PSCs assembled with Ta or Nb-doped TiO 2 blocking layer exhibited an evident promotion in short-circuit current density, and the best-performing PSCs had conversion efficiency enhancement from 13.66% (pure TiO 2 ) to 14.41% (Ta-doped TiO 2 ) and 14.29% (Nb-doped TiO 2 ). Moreover, the reproducibility of PSCs was preferable with 3% Ta and 3% Nb-doped TiO 2 blocking layer. Besides, the increased conductivity of doped TiO 2 compact layer efficiently suppressed the J-V hysteresis of PSCs under different scan directions. PL and EIS results further revealed that the doped-TiO 2 compact layer could accelerate electron transfer rate and decrease the recombination probability at TiO 2 /perovskite interface.