The progressive development of flexible transparent portable electronic devices is in urgent need of matching power sources. Flexible transparent supercapacitors (FTSCs) are the core resources due to their high optical transmittance, endurable mechanical flexibility, excellent electrochemical performance, and facilely accessible device configuration. This review organizes the rational design of nanostructured electrode materials toward FTSCs. First, the structure, mechanism, and property of FTSCs are introduced. Then, the design principles of diverse electrode materials are discussed to achieve flexible transparent conductive electrodes (FTCEs) with different figure of merits (both electrical FoMe and capacitive FoMc), mechanical strength, and environmental stability. Following the achievements in multifunctional FTSCs focusing on film‐supercapacitors, micro‐supercapacitors, electrochromic supercapacitors, photo‐supercapacitors, and battery‐like supercapacitors are also highlighted. Finally, the current challenges and future perspectives on viable materials in the construction of FTSCs to power portable electronics are outlined.
Covalent organic frameworks (COFs) exhibit great potential in the application of functional electronic devices. However, there has been no report of the precise fabrication of 3D all-in-one hollow micro/nanostructures based on COFs. Here, for the first time, all-in-one hollow dioxin-based COF-316 microflowers are synthesized measuring 5-7 µm and with interconnected hollow petals through a self-template strategy. The growth mechanism involves the collaborative process of self-assembly of nanoparticles, inside-out Ostwald ripening, and epitaxial growth. Due to the intrinsic porosity and interconnected hollow structure, COF-316 can uniformly composite with polypyrrole (PPy) through the "interior" and "exterior" functionalization, in which the hydrogen bond interaction enhances the charge transfer efficiency and structural stability in the charge/discharge process. The COF-316@PPy flexible transparent supercapacitors exhibit an areal specific capacitance (C A ) of 783.6 µF cm -2 at 3 µA cm -2 and longterm cycling stability. This work will boost research on the valuable design concepts of 3D hollow COF materials for energy storage devices.
2D conductive metal–organic frameworks (2D c‐MOFs) naturally possess high active sites, large specific surface areas, and fast ion transport for energy‐storage devices. However, the intelligent exploration of 2D c‐MOFs for the emerging flexible transparent supercapacitors (FTSCs) with excellent photoelectric property and electrochemical activity is rarely implemented. Herein, 2D conductive ultrathin Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11‐hexahydroxytriphenylene) film is synthesized on the indium tin oxide/polyethylene terephthalate (ITO/PET) substrate for flexible transparent conductive electrodes (FTCEs) through the layer‐by‐layer assembly method. The interconnected conductive frameworks possess the cooperative superiority of low internal resistance, fast electrolyte ion diffusion, and quick electron transfer. Cu3(HHTP)2‐15/ITO/PET FTCEs show high photoelectric property of T550 nm = 82.2% and Rs = 49.1 Ω sq−1, and high areal capacitance (CA) of 1700 µF cm−2. The corresponding symmetrical FTSCs (T550 nm = 62.1%) exhibit excellent CA of 939.2 µF cm−2 at the current density of 7 µA cm−2, superior rate capability (63.9% at 150 µA cm−2), long‐term cycling stability (85% after 3000 cycles), and mechanical flexibility under different bending angles. This work provides key insights into the design and synthesis of 2D c‐MOF films for flexible transparent energy‐storage devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.