Hierarchical metal nanomesh/microgrid structures for high performance transparent electrodes†
We report a comprehensive study on the optical and electronic properties of hierarchical metal nanomesh (NM)/microgrid (MG) structures to determine their performance as transparent conductors (TCs). The NM helps deliver or collect carriers locally while the lower resistance MG transports carriers over larger distances. The structures exhibit high uniformity of optical and electronic properties. Hierarchical Ag NM/Ag MG structures demonstrate 83% diffusive transmission at a sheet resistance of 0.7 Ω per square when fabricated directly on quartz and 81% at 0.7 Ω per square when fabricated directly on flexible plastic. The direct current to optical conductivity ratios σdc/σop of these structures are 2900 and 2300, respectively. This corresponds to over an order of magnitude reduction in sheet resistance with a negligible to slight reduction in transmission compared to NMs. The haze factor of these structures may be tuned by modifying the NM hole diameter. Furthermore, the hierarchical structures exhibit good durability under bending and heating.