Bendable & twistable oxide-polymer based hybrid electrochromic device: Flexible and multi-wavelength color modulation

Abstract

Flexible electrochromic (EC) technology has made huge progress in electronic industry for their applications in flexible displays, e-papers, e-curtains etc. The performance of device is the main concern while fabricating a flexible electrochromic device. In this paper, a solid state flexible electrochromic device (flex-ECD) has been demonstrated by combining the excellent EC performance of organic polymer and excellent stability of metal oxides which exhibits fast color switching and excellent stability after bending and twisting it for several times. For the fabrication of device, first Co₃O₄ and WO₃ powders have been synthesised and utilised as dopants in the two electrochromic active materials namely polythiophene (P3HT) and ethyl viologen (EV), respectively. Due to the doping of these nanomaterials the performance of the flex-ECD has been enhanced as measured in terms of coloration efficiency, switching time and stability. Additionally, the device shows color switching in their different wavelength regions between visible and NIR. The flex-ECD shows high stability with a few seconds of switching time and high coloration efficiency of 420 cm²/C. The device was first bent and subsequently twisted for several more times. After bending, the performance has been checked, exhibiting minimal change in switching time at 515 nm and 665 nm without compromising the coloration efficiency much. The device shows excellent stability after bending and twisting moments making it a good design for future wearable electronics.