Copper nanowires for next generation transparent conductors

In this work, copper nanowires (CuNWs) were synthesized for application in transparent conductors, as an exploratory work for the replacement of conventional indium-tin oxide (ITO) thin films. Two syntheses were made, one of them costing less than 4 € per synthesis. Numerous deposition methods were applied and several nanowire inks were used. The best ink was shown to be CuNWs with 7 wt% in isopropyl alcohol (IPA), and a newly developed method was designed to deposit NWs. The ink of CuNWs was deposited on top of interdigitated electrodes on glass. CuNWs on electrodes with gaps of 5, 10 and 30 μm registered a resistance as low as 68.07, 25.81 and 71.84 Ω, respectively. The films deposited directly on glass with top electrodes revealed a high electrical resistance, presumably due to high contact resistance. Inefficient intra-network welding (i.e., between NWs) was also responsible for the trend of increased resistance with higher number of consecutive depositions. Manual pressing was applied to the films, however, this process peeled off some CuNWs due to the lack of surface adhesion. So, numerous surface treatments were applied to glass surfaces, but then the surface roughness did not allow for a perfect deposition of aluminium contacts by e-beam. The optical properties of the films with different thicknesses (obtained with several subsequent depositions) were measured, with the optical transmittance decreasing for larger number of depositions. Best equilibrium in terms of electrical/optical properties was achieved with a single deposition, for which electrical resistance of 65 Ω (5 μm gap) and 90 % optical transmittance were obtained