Electrospray Preparation Of Copper Indium Sulfide Films And Their Applications As Counter Electrode For Dye-sensitized Solar Cells

Copper indium sulfide?CuInS₂,CIS?has been utilized as counter electrode?CE?in dye-sensitized solar cells?DSSCs?due to its suitable and reliable electrocatalytic activity,and good thermal/electrochemical stability.However,electrospray?ES?preparation of CIS film has never been reported.Thus,this thesis focuses on the development of ES preparation of CIS films,and their application in DSSC devices.Contents are as follows:Firstly,CIS materials were synthesisied via a simple one-pot method,employing Cu I,In?Ac?₃,and dodecanethiol as Cu,In,and S sources,respectively,along with oleic acid as surfactant.X-ray diffraction spectrum,Raman spectrum,Transmission electron microscopy and UV-vis absorption spectrum were conducted to investigate their structure,component,morphology/size and photophysical properties,respectively.The results indicate that the CIS product has high purity and small size,as well as its optical bandgap is about 1.9 e V.Secondly,with the assistance of thiourea additive,a stable CIS nanoparticles dispersion in n-hexane/ethanol mixture solvent was developed,and CIS films were sucessfuly prepared on the FTO substrates by ES method using this CIS dispersion.Experimental characterization prove that these CIS films have many advantages,e.g,high purity,porous structure,FTO-closely contacted,excellent catalytic properties and good electrochemical stability.In addition,it was found that the thickness of CIS films is easy to control by ES time variation,thereby facilitating the optimization of CIS film properties;and when ES-time is 10 min,CIS film shows the best catalytic performance.Thirdly and finally,these ES-prepared CIS films were assembled with dye-sensitized Ti O₂photoanodes to fabricate DSSC devices,and a power conversion efficiency of 8.81%was achieved in an optimized device under AM 1.5 illumination;constituting over 13%improvement compared with Pt control-device?7.77%?.Further analyses show that the porous network in the CIS CE and the close contact between FTO and CIS CE may account for this improvement.Moreover,electrochemical impedance spectroscopy indicates that the improvement is also partly attributed to the potential photovoltaic effect of CIS film.This study demonstrates the capability of ES method to fabricate CIS film and proves that the ES-prepared CIS film is a promising alternative to Pt CE in DSSC device.