Flexible, Transparent, Thickness-Controllable SWCNT/PEDOT:PSS Hybrid Films Based on Coffee-Ring Lithography for Functional Noncontact Sensing Device

Flexible transparent conductive films (FTCFs) as the essential components of the next generation of functional circuits and devices are presently attracting more attention. Here, a new strategy has been demonstrated to fabricate thickness-controllable FTCFs through coffee ring lithography (CRL) of single-wall carbon nanotube (SWCNT)/poly(3,4-ethylene dioxythiophene)-polystyrenesulfonate (PE-DOT:PSS) hybrid ink. The influence of ink concentration and volume on the thickness and size of hybrid film has been investigated systematically. Results show that the final FTCFs present a high performance, including a homogeneous thickness of 60-65 nm, a sheet resistance of 1.8 kohm/sq, a visible/infrared-range transmittance (79%, PET = 90%), and a dynamic mechanical property (>1000 cycle, much better than ITO film), respectively, when SWCNT concentration is 0.2 mg/mL, ink volume is 0.4 mu L, drying at room temperature. Moreover, the benefits of these kinds of FTCFs have been verified through a full transparent, flexible noncontact sensing panel (3 x 4 sensing pixels) and a flexible battery-free wireless sensor based on a humidity sensing mechanism, showing excellent human/machine interaction with high sensitivity, good stability, and fast response/recovery ability.