Colloidal synthesis of zincblende Cu₃InSnS₅ nanocrystals and their application in the thin-film solar cell

CuIn_0.7 Ga_0.3Se₂ thin-film solar cells with the over 23% power conversion efficiency are viewed as one the most promising devices in the solar energy field. A tremendous amount of efforts is spent to explore new absorbable layer material because of the rare of indium and gallium. Using abundant element to partly substitute In or Ga is considered an effective way. In this paper, colloidal oleylamine-capped Cu₃InSnS₅ quaternary nanocrystals are synthesized by hot injection way using mixed solvent of oleylamine and octadecene. The crystal structure, morphology, optical absorption, and valence state properties of as-synthesized oleylamine-capped Cu₃InSnS₅ nanocrystals are determined by using X-ray powder diffraction, transmission electron microscopy, UV–vis spectrometry, and XPS. The XRD analysis of Cu₃InSnS₅ quaternary nanocrystals possesses zincblende structure. UV–vis spectrometry characterization shows that the bandgap of the zincblende Cu₃InSnS₅ quaternary nanocrystals is 1.35 eV, which is suitable for the absorbable layer for the thin-film solar cells. The XPS illustrates valence state of four elements. The as-fabricated glass/ITO/CdS/Cu₃InSnS₅ nanocrystals/Al thin-film structure is obtained by spin-casting as-synthesized Cu₃InSnS₅ nanocrystals. The thin-film solar cell displays power conversion efficiency under AM1.5G illumination.