Electrospray preparation of CuInS2 films as efficient counter electrode for dye-sensitized solar cells

Abstract In this study, CuInS2 (CIS) thin films were prepared via electrospray (ES) method using a stable CIS nanoparticles dispersion with the assistance of thiourea additive. When the optimized CIS film was utilized as counter electrode (CE) for dye-sensitized solar cell (DSSC), a PCE of 8.81% was achieved under AM 1.5 illumination (100 mW cm-2), constituting over 13% improvement compared with platinum (Pt) control-device and being the highest values among CIS based DSSCs. Further analyses show that the porous network in CIS film and the close contact between the FTO and the CIS film may account for the improvement because it not only offers more sites for efficient catalysis of redox couples in the electrolyte but also promotes charge transfer in the DSSC device. Moreover, the CIS film in the DSSC device was also proved to contribute to the photocurrent generation. This work firstly demonstrates the capability of ES method to fabricate CIS films and proves that the ES-prepared CIS film is a promising alternative to Pt CE in DSSC devices. Furthermore, this method can be adopted to prepare the CIS absorber in thin-film solar cells, as well as to prepare functional films based on other semiconductors.