Effect of double blocking layers at TiO2/Sb2S3 and Sb2S3/spiro-MeOTAD interfaces on photovoltaic performance

Abstract

The effect of double blocking layers on the Sb₂S₃-sensitized all solid state solar cell are investigated. Thin layers of ZrO₂ (blocking layer 1, BL1) and ZnS (blocking layer 2, BL2) are introduced at the TiO₂/Sb₂S₃ and Sb₂S₃/hole transporting material (HTM) interfaces. The presence of BL1 is found to improve the open-circuit voltage (V_oc) from 457 mV to 618 mV, whereas BL2 improves mainly short-circuit current density (J_sc) from 11.1 mA cm⁻² to 14.0 mA cm⁻². Transient photovoltage confirms that the BL1 efficiently blocks charge recombination, responsible for the V_oc enhancement, whereas the BL2 has little effect on suppression of charge recombination. Surface modification of Sb₂S₃ by BL2, on the other hand, leads to recovery of Sb₂S₃ from the surface oxidized Sb₂O₅, which affects the J_sc increment. The present results suggest that the TiO₂/Sb₂S₃ interface is the main pathway for charge recombination rather than the Sb₂S₃/HTM interface. Double blocking layers enhanced the power conversion efficiency by 30%.