Sb₂(Se_1-xS_x)₃ Thin Film Solar Cells:Thin Films Preparation And Device Characterization

Antimony selenide（Sb₂Se₃） is a novel absorber material for inorganic thin film solar cells. It has a band gap of 1.10-1.20 eV, high absorption coefficient（>105 cm-1 at visible wavelength） and excellent photoresponse, permitting the construction of efficient photovoltaic devices. In addition, the earth-abundant and environmently friendly constituents of Sb₂Se₃ further increases its potential for commencial application. Therefore, Sb₂Se₃ is a promising absorber material for photovoltaic application.To futher increase the open-circuit voltage and conversion efficiency of Sb₂Se₃ solar cells, the Sb₂Se₃ absorber layer should be optimized to achieve more suitable band gap and band position. Similar to copper zinc tin sulfide（CZTS） thin films, we intend to introduce S to Sb₂Se₃ thin films and adjust the ratio between Se and S to regulate the band gap and band position, in order to improve device efficiency. At present, there is no relevant literature available regarding to this strategy.In this thesis, based on the preparation of Sb₂Se₃ thin films using rapid themal evaporation（RTE）, Sb₂(Se_1-xS_x)₃ thin films were successfully obtained through an in-situ sulfurization method during the RTE process. Different characteriazations, such as ultraviolet and visible spectrum（UV-Vis）, scanning electron microscopy（SEM）, X-ray energy dispersive spectroscopy（EDS）, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）, were applied to analyze the perporities of as-produced Sb₂(Se_1-xS_x)₃ thin films. Then, by adjusting the preparation process, a series of single-phase, highly crystalline Sb₂(Se_1-xS_x)₃ films with x=0.09, 0.20, 0.31 and 0.43 were successfully obtained. Ultraviolet photoelectron spectroscopy（UPS） were applied to calculate the band position and Fermi level position of those Sb₂(Se_1-xS_x)₃ thin films. Meanwhile, solar cells with superstrate ITO/CdS/Sb₂(Se_1-xS_x)₃/Au structure employing these films are fabricated, and the best composition were confirmed as Sb2（Se0.8S0.2）3 by correlating the statistics of device performance with the S content in the film. Finally, a champion device with 5.91 % solar conversion efficiency has been achieved through optimizing experimental process.