Qijin Huang

Highly flexible and transparent film heaters based on polyimide films embedded with silver nanowires

Highly flexible and transparent film heaters (TFHs) with superior mechanical and thermal stability were fabricated by embedding silver nanowires (AgNWs) into transparent polyimide (PI) films using a solution coating method. The fabricated AgNW/PI hybrid TFHs exhibited higher heating temperatures (∼96 °C) with lower input voltage (∼6 V), shorter response time (T < 40 s), and lower power consumption (160.6 °C cm2 W−1) than ITO/FTO heaters, as well as stability after repeated use. The AgNW/PI hybrid TFHs also showed excellent resistance to bending. After undergoing outer bending for a 1000 times, the change of sheet resistance was less than 18%. The effective embedment of the AgNW network in the surface of the transparent PI film not only decreased the surface roughness (Rrms < 1 nm) but also enhanced the resistance against oxidation and moisture. Potential applications of the AgNW/PI TFHs in window defogging and thermochromics are demonstrated.

Highly Thermostable, Flexible, Transparent, and Conductive Films on Polyimide Substrate with an AZO/AgNW/AZO Structure

Flexible transparent conductive films (TCFs) are used in a variety of optoelectronic devices. However, their use is limited due to poor thermostability. We report hybrid TCFs incorporation in both aluminum-doped zinc oxide (AZO) and silver nanowires (AgNWs). The layered AZO/AgNWs/AZO structure was deposited onto a transparent polyimide (PI) substrate and displayed excellent thermostability. When heated to 250 °C for 1 h, the change in resistivity (Rc) was less than 10% (Rc of pure AgNW film > 500) while retaining good photoelectric properties (Rsh = 8.6 Ohm/sq and T = 74.4%). Layering the AgNW network between AZO films decreased the surface roughness (Rrms < 8 nm) and enhances the mechanical flexibility of the hybrid films. The combination of these characteristics makes the hybrid film an excellent candidate for substrates of novel flexible optoelectronic devices which require high-temperature processing.

Flexible transparent conductive films on PET substrates with an AZO/AgNW/AZO sandwich structure

Hybrid transparent conductive films (TCFs) with a sandwich structure composed of aluminum-doped zinc oxide (AZO) and Ag nanowires (AgNWs) were deposited on polyethylene terephthalate (PET) substrates. The AZO layers were prepared at room temperature by RF magnetron sputtering. The AgNWs were synthesized by a modified polyol method and inserted into the AZO layers. The optical properties and conductivity can be modified by the number of spin-coating cycles of an AgNWs suspension. Typically, an AZO/AgNW/AZO hybrid film exhibited an optical transmittance of 80.5%, a sheet resistance of 27.6 Ω sq−1 and an optical haze of 14.9%. The increase in optical haze caused by the silver nanowires may be beneficial for applications in solar cells. The hybrid films presented excellent flexible stability, showing only minor resistance changes and no surface cracks compared with pure AZO films. The AZO layers acted as the protecting layers that enhanced the adhesive and thermal stability of the hybrid films. The resulting hybrid TCFs with an AZO/AgNW/AZO sandwich structure show potential applications in flexible electronics, energy storage and photovoltaic devices.

Roughening and islanding of monolayer Ge coverage on vicinal Si(001) surface

Roughening and islanding of monolayer Ge coverage on vicinal Si(001) surface has been studied using scanning tunneling microscope (STM). For a 3.9° miscut surface, planar buckled-dimer surface is a metastable state limited by a barrier, which can be overcome by a 680°C annealing. After the annealing, the metastable flat surface has been changed to a rough surface of small hills because of step-bunching, and on top of each hill, a 3 dimensional (3D) nanoscale island was observed. The mechanism of this roughening and islanding process have been discussed.

Application of inkjet printing technology in solar cell fabrication

With the increasing energy demand and consumption, the development and utilization of new energy have drawn much attention. Solar cell is a device which can convert sunlight energy into electricity by the photovoltaic effect, and solar cell has become a popular research project. Various printing techniques have been adopted in the fabrication of solar cell. Due to the unique advantages such as high material utilization rate, low cost, flexible, noncontact process and digital patterning, inkjet printing is believed to be the next generation solar cell manufacturing technology. The structure of solar cell and the recent progress in the application of inkjet printing technology in solar cell fabrication is reviewed. Detailed introductions to the application in metal electrode, transparent conductors and absorber layer of solar cell are presented. The potential and promising trends of inkjet printing technology in solar cell fabrication are also proposed. Inkjet printing technology will be an extremely important tool in solar cell fabrication in the near future.