Electrochromic Behavior of Highly Stable, Flexible Electrochromic Electrode Based on Covalently Bonded Polyaniline-Graphene Quantum Dot Composite

Abstract

Here in this work, a highly stable and flexible electrochromic film based on a composite of polyaniline and graphene quantum dots (PANI-fGQD), has been reported. To ensure the covalent attachment, monomer aniline was first attached to the negatively charged oxygenated groups present on the surface of GQDs followed by in-situ electrochemical polymerization for the composite. These amine sites act as nucleation sites for further growth. These electron rich oxygenated groups also act as secondary doping agents for hole dominating polyaniline (PANI). The prepared composite film has been found to show similar electrochemical response to that of PANI, but with more well-defined redox peaks and higher current densities. The composite (PANI-fGQD) exhibits improved electrochromic behavior with a color change from pale yellow to green to blue color as potential was scanned from −0.2 V to 0.8V. Pani-fGQD exhibits better optical contrast of 62% at 658nm and faster response time of 0.9s and 1.4s for coloration and bleaching, respectively, compared to pristine PANI. The composite also shows outstanding electrochemical stability of 15,000 cycles. The results present the significant potential of PANI-fGQD electrode for highly stable electrochromic application.

Electrochromism of Nanographenes in the Near‐Infrared Region

“…The application of NGs for EC materials has remained rare and has been achieved by the fabrication of composite materials [26, 27] . The EC function of chemically functionalized NGs [28] in the NIR region is, to the best of our knowledge, the first example.…”

Cobweb-Inspired Quintuple Network Structures toward High-Performance Wearable Electrochromic Devices with Excellent Bending Resistance

“…Flexible electrochromic devices (FECDs) possess the capability of reversibly altering their optical properties under applied voltage, which are essential in intelligent light management applications (e.g., wearable displays). − To succeed in wearable applications, a good FECD should survive a variety of long-term mechanical conditions, including bending, folding, and twisting, while maintaining its excellent flexibility and high electrochromic performance to a great extent. − However, due to the layered structure, most reported FECDs can only tolerate small mechanic conditions and are very prone to delaminate/fracture during applications, thus deteriorating their electrochromic (EC) cycling stability. − Meanwhile, under harsh mechanical conditions such as repeated bending, electrolytes tend to deform/leak and even cause short circuits. − In addition, the overall flexibility of the FECD is synergistically contributed by all of the layers . Malfunction of any component during applications can directly undermine the optical modulation and bending resistance of the flexible devices.…”

Functionalization of pristine graphene for the synthesis of covalent graphene–polyaniline nanocomposite

“…[13][14][15][16][17][18][19] Improved stability, electromagnetic and microwave absorption, and electrochemical performances have also been demonstrated through covalent bonding at graphene-polyaniline interface. [20][21][22][23][24][25] The graphene-PANI nanocomposites have been prepared from graphene oxide (GO) or reduced graphene oxide (rGO), owing to the low chemical reactivity of pristine graphene. 10,26,27 GO is synthesized by treating graphite with strong oxidation reagents such as H 2 SO 4 , KMnO 4 or H 3 PO 4 .…”