Exceeding 13% Power Conversion Efficiency of Cu(In,Ga)(S,Se)2 Thin-Film Solar Cells with AgNWs/TiOx Composite Transparent Conductive Window Layer

Abstract

Indium tin oxide (ITO) is usually served as the transparent conductive electrode of Cu(In, Ga)(S, -Se)₂ (CIGSSe) solar cells. However, ITO is fabricated by sputtering method, which will increase the cost of CIGSSe solar cells and prevent its large-scale market applications in the future. Hence, it is particularly important to develop low-cost transparent conductive window layers to replace the traditional ITO. Silver nanowires (AgNWs) are considered to be the most promising alternative to ITO. Compared with sputtered ITO, AgNWs have the advantages of high transmittance, low cost, and easy fabrication. Nevertheless, the poor adhesion and stability of AgNWs can prevent the transportation of carriers of CIGSSe solar cells. Here, we select amorphous TiO_x as an adjuvant to fabricate AgNWs/TiO_x composite transparent conductive layer to substitute the traditional ITO. Under the assistance of TiO_x matrix, not only the connection, adhesion, and stability of AgNWs are greatly enhanced, but also the surface roughness of AgNWs is also reduced. The influence of AgNWs concentration on the performance of CIGSSe solar cells is investigated. When the AgNWs concentration is 2.5 mg/mL, the transmittance and sheet resistance of AgNWs thin film are 93.35% and 93 Ω/sq, respectively, and the devices achieved the highest efficiency of 13.59%.