Layer-by-Layer Assembly of Conductive MOFs/PEDOT:PSS Hybrid Films with Superior Areal Capacitance for Flexible Transparent Supercapacitors

Flexible transparent supercapacitors (FTSCs) have been rapidly developed for next-generation intelligent electronics. Nonetheless, it remains challenging to balance the optical transparency and the areal capacitance of FTSCs because they are often contradictory. Two-dimensional (2D) metal–organic frameworks (MOFs) have emerged as appealing electrode materials due to their ultrathin nanosheets and accessible active sites; however, the intrinsically poor electrical conductivity of 2D MOFs hinders their advances in FTSCs. Herein, a layer-by-layer assembly strategy is proposed to fabricate the transparent conductive electrode of MOFs/PEDOT/PSS hybrid films, by employing NiCo-BDC (BDC = 1,4-benzenedicarboxylate) nanosheets and conductive poly(3,4-ethylenedioxy-thiophene)-poly(styrenesulfonate) (PEDOT/PSS). NiCo-BDC/PEDOT/PSS can synergistically utilize abundant redox-active sites of 2D NiCo-BDC and high electrical conductivity of PEDOT/PSS, enabling fast charge transport and electrolyte ion diffusion. As a consequence, the NiCo-BDC/PEDOT/PSS FTSCs show a superior areal capacitance of 4.0 mFcm –2, a high optical transparency of 56%, an outstanding energy capacity of 110 μW h cm –2 at 0.13 mW cm –2, excellent mechanical flexibility, and cycle stability. This work opens a new avenue for the fabrication of transparent conductive electrodes and is promising for high-performance flexible transparent energy storage devices.