Layer‐by‐Layer 2D Ultrathin Conductive Cu3(HHTP)2 Film for High‐Performance Flexible Transparent Supercapacitors

Abstract 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 Cu 3 (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. Cu 3 (HHTP) 2 ‐15/ITO/PET FTCEs show high photoelectric property of T 550 nm = 82.2% and R s = 49.1 Ω sq −1 , and high areal capacitance ( C A ) of 1700 µF cm −2 . The corresponding symmetrical FTSCs ( T 550 nm = 62.1%) exhibit excellent C A 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.