Investigation on effect of blocking layer in perovskite sensitized pure and aluminium doped ZnO photoanode solar cell

ZnO is a promising candidate as low cost, porous semiconductor material for photoanodes in a dye sensitized solar cell. In this work, we investigate the performance of pure ZnO nanoparticles (ZNPs), Al₂O₃ doped ZnO (Al@ZNPs) and ZnO/Nb₂O₅ core–shell structure of photoanode material. These electrodes were sensitized with a pervoskite CH₃NH₃SnCl₃ sensitizer. To study the effect of the Al₂O₃, Nb₂O₅ treatment with ZnO, the J–V and EIS parameters, the current density (Jsc),Open circuit voltage (Voc), fill factor (FF), electron life time (τ_n), electron mobility (µ) and charge collection efficiency (ƞ_cc) are calculated for the fabricated solar cells and the results are compared. It was found that the Al₂O₃ doped ZnO with the sensitizer CH₃NH₃Sncl₂ showed the highest efficiency of 9.41% under 100 mW/cm² irradiation. The electron impedance spectroscopy revealed that the charge collection efficiency (ƞ_cc) of the solar cells is in the order of PSSC3 > PSSC4 > PSSC2 > PSSC1. In this work, the effect of blocking layer (Ta₂O₅) is also discussed. From the J–V and EIS analysis, the effect of blocking layer is appreciable and it is useful to increase the efficiency of the solar cell by the way of reducing the recombination of charge carriers process. Therefore, the increase of photocurrent is mainly due to the combined effect of the sensitizer competence and blocking layer.