We fabricated Cu­(In,Ga)­(S,Se)2 (CIGSSe) solar cells using aqueous spray based deposition, which is inexpensive and covers a large area. To apply the sprayed film to a photoabsorber of a solar cell, post-sulfo-selenization was carried out. Through the sulfo-selenization process, we were able to fabricate various S-alloyed CIGSSe films from S/(S + Se) = 0 (S-0.0) to S/(S + Se) = 0.4 (S-0.4). CIGSSe solar cells were made with the S-alloyed CIGSSe absorbers. Power conversion efficiency of CIGSSe solar cell was found to be increased with S-alloying up to S-0.3, and the best efficiency of 10.89% was obtained with the S-0.3 CIGSSe absorber. Comparison study of S-alloyed CIGSSe solar cells showed that enhanced efficiency in S-0.3 solar cell is due to the increased open-circuit voltage and an improved fill factor, which is induced by S-alloying. In addition, admittance spectroscopy revealed that the defect density of the deep level was developed in the S-alloyed S-0.3 CIGSSe absorber. However, the defect density was observed to be rather reduced. Details of characterization and analysis results are discussed in this paper.

As a Cd-free buffer, In2S3 buffer has been used in Cu(In,Ga)Se2 (CIGS) solar cells.

A method for in situ Al 2 O 3 incorporation into a Cu 2 ZnSn(S,Se) 4 (CZTSSe) absorber and its effect on solar cell performance is reported. Al 2 O 3 -incorporated CZTSSe films can be prepared by spraying a precursor solution containing Al metal salt dissolved together with Cu, Zn, and Sn metal salts and thiourea. X-ray photoemission spectroscopy (XPS) and field-emission transmission electron microscopy (FESEM) reveal the existence of an Al 2 O 3 phase in the CZTSSe film. X-ray diffraction (XRD) and Raman spectroscopy indicate that Al 2 O 3 incorporation (Al: 0%-2%) does not have a noticeable effect on the crystallization process through postselenization and does not change the lattice parameters of the selenized CZTSSe. However, optimal Al 2 O 3 incorporation is found to reduce the defect level and defect density, as confirmed by various characterization methods, such as 442 nm Raman spectroscopy, photoluminescence, admittance spectroscopy, and temperature-dependent current density measurements. In addition, Al 2 O 3 incorporation reduces the Urbach energy and back-contact barrier height. Al 2 O 3 incorporation is found to induce enhancement of Na and O concentrations in the absorber, which facilitates defect passivation effects. Owing to the observed beneficial effects of Al 2 O 3 incorporation, the device performance is significantly enhanced, achieving a maximum power conversion efficiency of 11.76%.