Efficiency Improvement of Narrow Band Gap Cu(In,Ga)(S,Se) Solar Cell with Alkali Treatment via Aqueous Spray Pyrolysis Deposition.

The chalcopyrite Cu(In,Ga)(S,Se) (CIGSSe) solar cell with a low band gap is a promising candidate for use as the bottom cell in high-efficiency tandem solar cells. In this study, we investigated narrow band gap CIGSSe solar cells, both with and without alkali treatment. The CIGSSe absorbers were fabricated using aqueous spray pyrolysis in an air environment, with the precursor solution prepared by dissolving constituent metal salts.

Insights into High-Efficiency Ag-Alloyed CZTSSe Solar Cells Fabricated through Aqueous Spray Deposition.

Kesterite CuZnSnSe (CZTSe), CuZnSn(S,Se) (CZTSSe), and CuZnSnS (CZTS) solar cells show considerably lower open-circuit voltages than their theoretical values. The large open-circuit voltage deficiency () hinders the improvement of the power conversion efficiency (PCE) and the development of the pathway to mass production of kesterite solar cells. The main reason behind the is considered to be the low formation energy of Cu/Zn disorders and their highly distributed defect complexes.

Sulfur-Alloying Effects on Cu(In,Ga)(S,Se) Solar Cell Fabricated Using Aqueous Spray Pyrolysis.

We fabricated Cu(In,Ga)(S,Se) (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.