Improving the multi-step fabrication approach of copper nanofiber networks based transparent electrode for achieving superb conductivity and transparency

Transparent Conductive Electrode (TCE), as an essential part of the optoelectronic devices, has become popular owing to its unique properties such as high optical transmittance and conductivity. Among utilized materials for fabrication of TCE, copper nanofibers (NFs)-network have been attracting much attention due to its extraordinary properties such as low sheet resistance, the scalable manufacturing and low-cost fabrication method. However, many challenges exist in the way of multi-step fabrication of network to increase the NFs continuity and consequently, improvement of their electrical conductivity as TCE. Herein, we report a deep investigation of the effective parameters on diameter and the continuity of network by tracing the impact of variations in spinning voltage, polymer concentration of electrospinning solution, temperatures and heating rates of heat treatment processes. The FESEM results demonstrated that the proper diameters of fibers could be gained using the optimized spinning voltage and a polymer concentration of 12 kV and 8 wt%, respectively. Also, the FESEM images indicated the most proper heating rates of calcination and reduction processes are 4 degrees C min(-1) and 2 degrees C min(-1), respectively. In addition, the results of other analysis such as XRD, TGA, DTA and FTIR determined the appropriate temperatures of calcination and reduction are 500 degrees C and 300 degrees C, respectively, to the formation and stabilizing of continuous (NFs)-network. Using these values resulted in the formation of a perfect NFs network having required fused junctions with 20 Omega sq(-1) sheet resistance and 81% transparency.