Random mesh-like Ag networks prepared via self-assembled Ag nanoparticles for ITO-free flexible organic solar cells

Highly-transparent and flexible random mesh-like Ag networks formed by self-assembled Ag nanoparticles for use in transparent and flexible electrodes for ITO-free flexible organic solar cells (FOSCs) was demonstrated. By transferring a self-assembled Ag nanoparticle network onto a PET substrate, embossed and intaglio-type mesh-like Ag network electrodes were fabricated. Electrical, optical, morphological, and mechanical properties of the embossed and intaglio-type mesh-like Ag network electrodes were compared in detail. Although both mesh-like Ag networks exhibited similar sheet resistance, optical transmittance, and flexibility, the intaglio-type Ag networks were advantageous to use as transparent electrodes for FOSCs due to the high aspect ratio of emboss-type Ag networks. Regardless of organic active materials, FOSCs with intaglio-type Ag networks exhibited better performance than FOSCs with emboss-type Ag networks due to ease in forming uniform organic layer coatings on the intaglio-type Ag networks embedded in the substrate. This indicated that intaglio-type mesh-like Ag network electrodes are a promising flexible and transparent anode for printable ITO-free FOSCs.