Chao Chen,Yonggao Jia,Dan Jia,Shuxin Li,Shulin Ji,Changhui Ye
Silver nanowire transparent conductive films have been proposed as a promising candidate to replace indium tin oxide films for electronic applications. Stable ink with a high loading amount of silver nanowires is essential for the scale-up of the production of transparent conductive films considering the storage need due to separated procedures of nanowire synthesis and film formation. It is very hard to re-disperse the nanowires if irreversible aggregation happens during storage for coating. The paradox of stabilizing the concentrated nanowire ink and facile utilizing of the ink for highly conductive films with a low junction resistance at the joint points of organic stabilizer-capped silver nanowires has to be solved. A two-step method has been provided to overcome the difficulty in this work. First, a silver nanowire ink with the loading amount of 5 mg mL−1 is formulated, which is stable for more than three months under normal conditions. The success in maintaining the long-term stability lies in applying an appropriate amount of surfactant and choosing organic solvents with appropriate mixing ratios to strengthen the interaction of the surfactant with the silver nanowires and to decrease the free energy through enthalpy of mixing silver nanowires into the solvent for aggregation prevention. Second, the concentrated ink at any time is simply washed a suitable number of times and diluted to a uniform dispersion for coating of TCFs with excellent optical and electrical performance, having a figure of merit σDC/σOP (ratio of the electrical conductance to optical conductance) as high as 228. The viability of treating silver nanowires in large quantity paves the way for real industrial applications.
Developing an advanced transparent conductive electrode (TCE) as a substitute for the fragile and high-cost indium tin oxide (ITO) is the top priority in the coming smart electronics era. Although two-dimensional transition metal carbides and nitrides (MXenes) have revealed great potential in the competition, the figure of merits (FoMe, defined as the ratio of direct current conductivity to optical conductivity) of reported MXenes TCEs are far below the minimum industrial requirement. Herein, we report on the breaking of FoMe limitation by a hybrid nanoimprint-blading technique to construct embedded MXene grids, where the fine slot channels are filled with MXene flakes and the space beyond is left empty, allowing more visible light to pass through, thus substantially improving the transmittance. Such a strategy decouples the correlation between transmittance and sheet resistance and achieves their individual regulation. As a result, we obtain an ultrahigh FoMe (∼84) surpassing most of other nonmetal TCEs and even being competitive to ITO. We demonstrate the application of MXene grid TCE in the electrochromic device, showing satisfactory switching time and excellent stability (>38,000 cycles). This work opens vast opportunities for MXenes to construct advanced flexible electronics for industrial applications.
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