We demonstrate a facile approach to fabricate Ag nanomesh transparent conducting electrodes (TCEs) on a flexible substrate using nanoimprint lithography (NIL) and transfer printing without a conducting polymer. The Ag nanomesh TCEs exhibited a high transmittance of $88% and a low sheet resistance of $15 U sq À1 as well as superior mechanical flexibility. Furthermore, flexible inverted organic solar cells (IOSCs) with Ag nanomesh TCEs exhibited a power conversion efficiency (PCE) of $7.15% under 100 mW cm À2 AM 1.5G illumination as well as superior long-term stability under ambient conditions. This type of highly flexible and transparent Ag nanomesh electrode is a promising candidate for use with TCEs in various optoelectronic devices.Organic solar cells (OSCs) have attracted signicant interest because of their great potential to become a green energy source with a large-area, light-weight, mechanical exibility, and low cost processes by roll-to-roll manufacturing. 1-3 Recently, there have been extensive investigations of inverted organic solar cells (IOSCs) with an inverted structure, using modied indium tin oxide (ITO) as the cathode (the ITO is modied by an n-type metal oxide, a conjugated polyelectrolyte, and a self-assembled monolayer). 4,5 Compared with conventional OSCs (COSCs), the IOSCs demonstrate better long-term air stability by avoiding the need for a corrosive and hygroscopic hole transport layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and a low work function metal cathode, both of which are detrimental to the device lifetime. 4,5 Furthermore, IOSCs can also offer vertical phase separation and concentration gradient in the photoactive layer, which is naturally selfencapsulated because air stable metals are used as the top electrode. 6-9 Indium tin oxide (ITO), which is commonly used as a transparent conductive electrode (TCE), is not suitable as a transparent electrode for exible devices because it is brittle and cracks easily under mechanical stress. 8 Moreover, owing to the rapid depletion of elemental indium and the costs associated with the various vacuum deposition techniques used to produce ITO, its continued use is proving to be expensive. This, in turn, is signicantly hindering the realization of low-cost and easy-to-fabricate exible optoelectronic devices.These key issues in the use of ITO are being addressed by the emergence of next-generation exible transparent materials such as carbon nanotubes (CNTs), 9-11 graphene, 12-17 conducting PEDOT:PSS, 18-22 silver nanowires (Ag NWs), 23-28 and metal meshes. 29-37 The performance of these materials for applications as TCEs is strongly affected by two parameters: optical transmittance and electrical conductivity. However, achieving high conductivity and high optical transmittance has been a challenge because these two properties are usually inversely proportional, and this oen results in optoelectronic performance characteristics far inferior to those of the ITO.Recently, CNTs have been extensively investig...