Inverted Layer-By-Layer Fabrication of an Ultraflexible and Transparent Ag Nanowire/Conductive Polymer Composite Electrode for Use in High-Performance Organic Solar Cells

Abstract

A highly flexible and transparent conductive electrode based on consecutively stacked layers of conductive polymer (CP) and silver nanowires (AgNWs) fully embedded in a colorless polyimide (cPI) is achieved by utilizing an inverted layer-by-layer processing method. This CP-AgNW composite electrode exhibits a high transparency of >92% at wavelengths of 450-700 nm and a low resistivity of 7.7 ?(-1), while its ultrasmooth surface provides a large contact area for conductive pathways. Furthermore, it demonstrates an unprecedentedly high flexibility and good mechanical durability during both outward and inward bending to a radius of 40 m. Subsequent application of this composite electrode in organic solar cells achieves power conversion efficiencies as high as 7.42%, which represents a significant improvement over simply embedding AgNWs in cPI. This is attributed to a reduction in bimolecular recombination and an increased charge collection efficiency, resulting in performance comparable to that of indium tin oxide-based devices. More importantly, the high mechanical stability means that only a very slight reduction in efficiency is observed with bending (<5%) to a radius of 40 m. This newly developed composite electrode is therefore expected to be directly applicable to a wide range of high-performance, low-cost flexible electronic devices.