Here in this work, two electrochromic systems have been prepared by functionalizing di-pentyl viologen (DPV) and di-heptyl viologen (DHV) with graphene quantum dots (GQDs). Strong molecular forces like cation-$\pi$interactions, π–π stacking interactions, electrostatic interactions, etc., ensure an adequate interaction between GQDs and viologens, hence, responsible for stabilizing the electrochromic system. All solid electrolyte-free electrochromic devices have been fabricated by dispersing DPV-GQD and DHV-GQD in poly(vinyl)alcohol (PVA) gel. Electrochemical behavior and electrochromic responses of the fabricated devices were investigated using chronoamperometry, cyclic voltammetry and in situ UV–vis spectroscopy. Both devices were found to work efficiently without the help of supporting electrolytes. Both DPV-GQD and DHV-GQD devices exhibit high optical contrast of 53.4% and 60%, with superior coloration efficiency of 143.9 cm²/C and 66 cm²/C, respectively. Swift electrochromic responses of 4.4 s/3.5 s and 6.2 s/2.5 s have been recorded for coloration/bleaching for DPV-GQD and DHV-GQD devices, respectively. Fabricated DPV-GQD device was found to retain 73% of its initial optical contrast while DHV-GQD depicts retention of only 63% after 3000 cycles. The superior coloration efficiency and balanced response time of DPV-GQD make it a potential material for the device application.

在这项工作中，通过用石墨烯量子点 (GQD) 对二戊基紫精 (DPV) 和二庚基紫精 (DHV) 进行功能化，制备了两种电致变色系统。强分子力，如阳离子-$\pi$相互作用，π-π堆积相互作用，静电相互作用等，确保GQDs和紫精之间的充分相互作用，因此负责稳定电致变色系统。所有无固体电解质的电致变色器件都是通过将 DPV-GQD 和 DHV-GQD 分散在聚乙烯醇 (PVA) 凝胶中制成的。使用计时电流法、循环伏安法和原位紫外-可见光谱法研究了所制造器件的电化学行为和电致变色响应。发现这两种设备都可以在没有支持电解质的帮助下有效工作。DPV-GQD 和 DHV-GQD 器件均表现出 53.4% 和 60 % 的高光学对比度，具有 143.9 cm ² /C 和 66 cm ²的卓越着色效率/C，分别。对于 DPV-GQD 和 DHV-GQD 器件的着色/漂白，分别记录了 4.4 s/3.5 s 和 6.2 s/2.5 s 的快速电致变色响应。发现制造的 DPV-GQD 设备保留了 73% 的初始光学对比度，而 DHV-GQD 描绘了 3000 次循环后仅保留 63%。DPV-GQD 卓越的着色效率和均衡的响应时间使其成为器件应用的潜在材料。