Exploring innovative synthetic solutions for advanced polymer-based electrochromic energy storage devices: Phenoxazine as a promising chromophore

The current investigation offers an innovative synthetic solution regarding electrochromic (EC) and energy storage applications by exploring phenoxazine (POZ) moiety. Subsequently, three POZ-based polymers (polyimide, polyazomethine, and polyamide) were synthesized to ascertain the superior performer. The polyamide exhibited remarkable attributes, including high redox stability during 500 repetitive CVs, optical contrast of 61.98%, rapid response times of 1.02 and 1.38 s for coloring and bleaching, EC efficiency of 280 cm2 C-1, and decays of the optical density and EC efficiency of only 12.18% and 6.23% after 1000 cycles. Then, the energy storage performance of polyamide PA was tested, for which the following parameters were obtained: 74.7 F g-1 (CV, scan rate of 10 mV s-1) and 118 F g-1 (GCD, charging current of 0.1 A g-1). Then, the polyamide was tested in EES devices, which yielded the following EC parameters: an optical contrast of 62.15%, response times of 9.24 and 5.01 s for coloring and bleaching, EC efficiency of 178 cm2 C-1, and moderate decays of 20.25% and 23.24% for the optical density and EC efficiency after 500 cycles. The energy storage performance included a capacitance of 106 F g-1 (CV, scan rate of 0.1 mV s-1) and 9.23 F g-1 (GCD, charging current of 0.1 A g-1), capacitance decay of 11.9% after 500 cycles, and 1.7 V retention after 2 h. Also, two EES devices connected in series powered a 3 V LED for almost 30 s.