An ultrathin SiO2 blocking layer to suppress interfacial recombination for efficient Sb2S3-sensitized solar cells

Interfacial charge recombination is a serious problem in semiconductor-sensitized solar cells which severely limits the power conversion efficiency. Herein, an ultrathin SiO2 blocking layer was introduced to the TiO2 surface to suppress the interfacial recombination in Sb2S3-sensitized solar cells. The SiO2 blocking layer was deposited by a simple chemical bath method. Due to the unique features of the SiO2 layer, the Sb2S3 sensitizer shows a remarkable change in the morphology after SiO2 coating, forming numerous irregular large crystals which did not bring a negative impact. Electrochemical impedance spectra and open-circuit voltage-decay analysis confirm that the SiO2 layer efficiently suppresses the interfacial recombination at the TiO2/Sb2S3 interface which is the major recombination path in the solar cells. As a result, the device exhibits remarkably enhanced open-circuit voltage, fill factor and power conversion efficiency.