Hierarchical Silver Network Transparent Conducting\nElectrodes for Thin-Film Solar Cells

Abstract

Flexible\nmetal network transparent conducting electrodes (TCEs)\nare expected to be the most promising candidates to replace indium\ntin oxide (ITO) due to their excellent electro-optical performance\nand mechanical flexibility. However, to successfully replace ITO with\nthe metal network TCEs, more studies on their suitability for integration\nwith real devices are needed. In this study, we developed a hierarchical\nsilver network simultaneously meeting the requirements of (i) low\nsheet resistance, (ii) high optical transmittance, (iii) excellent\nmechanical flexibility, and (iv) good integration into a thin-film\nsolar cell. The hierarchical silver network consists of a silver micromesh\nas the main framework and silver nanowires as the secondary framework.\nThe hierarchical network provides a figure of merit similar to that\nof the individual micromesh and much higher than those of silver nanowires\nand ITO. When applied to Cu­(In, Ga)­Se₂ thin-film solar\ncells, the hierarchical network achieved better device performance\nthan the micromesh. In the hierarchical network, the micromesh enables\nlow sheet resistance and the silver nanowires enable excellent integration\nwith the device while maintaining high optical transmittance. Thus,\nconsidering the aforementioned requirements, the hierarchical network\ncould be one of the best candidates as a TCE for Cu­(In, Ga)­Se₂ thin-film solar cells.