Formation of p-type Cu3BiS3 absorber thin films by annealing chemically deposited Bi2S3-CuS thin films

Formation of the ternary compound Cu3BiS3 during annealing of chemically deposited CuS (similar to 0.3 mu m) films on Bi2S3 film (similar to 0.1 mu m on glass substrate) is reported. The interfacial atomic diffusion leading to the formation of the compound during the annealing is indicated in x-ray photoelectron depth profile spectra of the films. The formation of Cu3BiS3 (Wittichenite, JCPDS 9-488) is confirmed by the x-ray diffraction (XRD) patterns. The films are optically absorbing in the entire visible region (absorption coefficient 4 x 10(4) cm(-1) at 2.48 eV or 0.50 mu m) and are p-type with electrical conductivity of 10(2)-10(3) Omega(-1) cm(-1). Potential applications of these films as optical coatings in the control of solar energy transmittance through glazings and as a p-type absorber film in solar cell structures are indicated.