A fully electrospray-processible electrochromic supercapacitor for smart window applications

Electrochromic (EC) technology has undergone significant advancements, enabling its integration into next-generation optoelectronic and energy storage systems. In a typical electrochromic device (ECD), the choice of active organic materials and polymer electrolytes plays a critical role in determining device performance. Herein, we report a fully electrospray-processable electrochromic supercapacitor that combines a carbazole-based material (4,4?-bis(9H-carbazol-9-yl)-1,1?-biphenyl-CBP) as the anodic layer with PEDOT:PSS as the cathodic counterpart. Electrospray deposition was employed to fabricate uniform, nanostructured thin films of CBP and PEDOT:PSS with enhanced porosity, thereby improving electrolyte accessibility and interfacial contact. Morphological features were systematically evaluated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), while crystalline-to-amorphous transitions induced by electrospray deposition were confirmed by X-ray Diffraction (XRD) analysis. The resulting electrochromic supercapacitor devices exhibited pronounced optical modulation, with a transmittance contrast of up to 50%, reversible switching behavior with coloration and bleaching times as low as 1.9 s and 2.4 s, and excellent electrochemical durability, retaining over 95% of the initial capacitance after 10,000 charge-discharge cycles. In addition, high areal capacitance values were achieved, highlighting the efficient charge storage capability of the electrospray-processed architecture. These results demonstrate that electrospray processing provides a scalable and versatile route for fabricating multifunctional organic electrochromic supercapacitors, paving the way for their implementation in energy-efficient smart window applications. © 2026 Elsevier B.V.