R. Padhan, M. Susner, R. Rao, S.A. Kadam, A. Wali, R. Divan, W.C. West, A.V. Sumant, N.R. Pradhan
Jackson State University,
United States
Keywords: 2D Ferroelectric Materials, micro-capacitor, heterostructure energy-storage device
Summary:
Future electronic devices required ultra-high energy storage, greater power densities and quick charging and discharging capacities. A suitable light weight thin film materials with greater flexibility of processing, high dielectric constant and breakdown voltage is the ultimate choice for next generation energy storage application. Dielectric capacitor provides greater power densities than batteries could have great potential for the energy storage for portable electronics and applicable in space if energy density can be improved. Here, we present the rational approach to design ultra-high energy storage capacitors using high-k pristine two-dimensional (2D) dielectric materials. This design leverages the unique properties of the layered van der Waals ferroelectric semiconductor CuInP2Se6 (CIPSe) with varying thickness constructed to form micro-capacitor. CIPSe is considered as in a paraelectric phase with dielectric properties at room temperature. It undergoes ferroelectric phase at 234 K suggested that the it can be polarized very easily by applied electric field. We fabricated the CIPSe dielectric capacitor by dry transferring a thin layer of graphene on to the CIPSe flakes exfoliated on a Si/SiO2 substrate and then subsequently the heterostructure of CIPSe/graphene was transferred onto the Au coated substrate to form a Au/CIPSe/Graphene heterostructure capacitor. To ensure precise electrical connections, we employed contact Atomic Force Microscopy (C-AFM) by connecting the graphene flake with a conducting AFM tip to measure polarization and capacitance, on Au/CIPSe/Graphene micrometer size capacitor. Polarization was measured as a function of applied electric field strength and capacitance as a function of frequency to elucidate the energy density and dielectric constant of the capacitor at room temperature. We observed ultra-high energy density of ~100 J/cm3 at the E = 120 MV/m and maintaining high efficiency (>90%) at room temperature with minimal hysteresis loss. The observed energy density is much higher than the conventional dielectric capacitors. This work paves the way for next-generation solid-state capacitors that combine high power density with ultra-high energy storage capacity in few atomic layer’s materials crucial for applications in electric vehicles, renewable energy, portable electronics as well as in space mission.