PANI doped with carbon quantum dots for the asymmetric high-performance solid-state electrochromic supercapacitor

The growing trend towards more intelligent technological products demands greater functional integration. The electrochromic supercapacitor (ECSC), which combines multicolor electrochromic behavior with energy storage, enhances user experience by visualizing the device's energy status. A key challenge for practical applications is to develop scalable, low-cost methods for producing high-performance electrochromic supercapacitors. In this work, we synthesize the polyaniline (PANI) doped with carbon quantum dots, which exhibits excellent capacitive and electrochromic performance, and employ a spray-coating technique to fabricate the working electrode. Coupled with a transparent V 2 O 5 @PEDOT layer as the ion-storage counter electrode, a novel asymmetric solid-state ECSC is assembled. The ECSC demonstrates high energy/power density (51.87 μWcm −2 /4.02 μWhcm −2 –980.41 μWcm −2 /2.914 μWhcm −2 ), fast switching times (t c  = 0.75 s, t b  = 2.61 s), outstanding coloring efficiency (221.6 cm 2  C −1 ) and cycling stability (over 5000 cycles). The distinct color transitions enable intuitive visual assessment of the device's energy storage level. Moreover, the spray-coating method facilitates large-area and patternable production, offering a promising route for developing next-generation smart and portable multifunctional electronic devices.