MoO3 surface passivation on TiO2: An efficient approach to minimize loss in fill factor and maximum power of dye sensitized solar cell

Highlights: • MoO₃ surface passivation on nanocrystalline TiO₂ enhanced the DSSC performance by 14%. • Effect of parasitic resistances on DSSC performance can be engineered by MoO₃ passivation. • Passivation time plays an influential role on the DSSC performance due to the thickness of MoO₃. The present study demonstrates the possibility for improving the performance of dye sensitized solar cell (DSSC) only by minimizing the loss in fill factor (FF) and maximum power point (P_MAX) which can be achieved by passivating the nanocrystalline titanium dioxide (TiO₂) using physical vapor deposited molybdenum trioxide (MoO₃) thin films. The effect of MoO₃ coated TiO₂ on charge carrier transport was examined in resulting DSSCs and observed that ∼14% enhancement in efficiency is possible for 5 min passivation of MoO₃ on TiO₂. The physical vapor deposited MoO₃ films were ∼75% transparent in the spectral range of 350–800 nm with an optical bandgap of ∼3.1 eV. The wide bandgap MoO₃ films facilitate the incoming photons to reach the sensitizing dye to generate excitons. The 14% enhancement in the performance of DSSC by MoO₃ passivation is observed through improving only the FF and P_MAX while it does not contribute anything significantly to current density and open circuit voltage. Electrochemical impedance spectroscopic studies further confirmed these observations through photo-electron lifetime, which remains constant both in the bulk of pristine TiO₂ and MoO₃ passivated TiO₂ and it further confirms the effect of MoO₃ passivation on FF and P_MAX in DSSCs.