Effect of substrate temperature on the performance of ultrasonically sprayed PEDOT:PSS-AgNWs transparent conductive films for electrochromic devices

The concentration polarization occurring during reactions between counter electrodes and electrolytic solutions in electrochromic (EC) devices affect the performance of these devices. This study used ultrasonic spray coating to prepare thin films consisting of poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate-silver nanowires (PEDOT:PSS-AgNWs)/indium tin oxide (ITO) as the counter electrode of tungsten trioxide (WO3)-based EC devices. Using ultrasonic spray coating to prepare thin films under various substrate temperatures produces distinct film formation mechanisms. Moreover, the surface topography of the thin films is considerably affected, thereby influencing the coloration efficiency (CE) of the EC device. PEDOT:PSS-AgNWs have excellent conductivity and light transmittance. In addition, AgNWs with roughened surfaces can reduce concentration polarization, a phenomenon observable during redox reactions in EC devices. AgNWs can also increase the reversibility of intercalation and deintercalation in the WO3 active layer by ions in the electrolytic solution. The transmittance analysis revealed that the present device had a transmittance modulation and a CE of up to 72.93% and 222.61 cm(2)/C, respectively. In sum, ultrasonic spray coating preparation of PEDOT:PSS-AgNWs on an ITO glass substrate as the counter electrode resulted in excellent EC device performance. This method has high potential in future development of high-performance EC devices.

Automated summary

This study investigated the use of ultrasonic spray coating to prepare PEDOT:PSS-AgNWs/ITO thin films as the counter electrode of WO3-based EC devices. Different film formation mechanisms were observed under various substrate temperatures, and the surface topography of the thin films significantly affected the CE of the EC device. PEDOT:PSS-AgNWs exhibited excellent conductivity and light transmittance, and reduced concentration polarization while increasing the reversibility of intercalation in the WO3 active layer. The analyzed results showed high transmittance modulation and CE for the device.