MA02.08.17 : Nanostructured PEDOT Polymer-Graphene Composite Structures for Flexible and Stretchable Electronics Applications

5:00 PM–7:00 PM Apr 5, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Shady Abd El-Nasser1 Mahmoud Sakr1 Mohamed Serry1

1, The American University in Cairo, New Cairo, , Egypt

One of the major drawbacks for successful application of graphene in energy storage and conversion applications is its cone shaped band gap.Poly (3,4-ethylenedioxythiophene) (PEDOT) has shown its applicability in several applications i.e. flexible devices, energy harvesting, energy storage, electrochemical supercapacitors and solar cells. In this work we discuss the synthesis and characterization of PEDOT/Graphene composite which has led to 196 enhancement in current output. The new composite structure is consisting of nanostructured conducting polymer deposited on the surface of graphene-Schottky-diode (Conducting-Polymer/Graphene/Pt/n-Si). PEDOT was selected as the organic semiconductor material because of its low band gap (1.5−1.7 eV), long-term stability as well as good electrical conductivity. Pt thin film was deposited using Atomic Layer Deposition (ALD) on a substrate of an N-silicon wafer and graphene layers were deposited using Plasma Enhanced Chemical Vapor Deposition (PECVD). Fabrication and Experimental section included spin coating (PEDOT) with different thicknesses and depositing different Pt thicknesses and I-V and I-t measurements were done for the samples under dark condition to neglect opto-electric effect to study the current enhancement. I-V measurements showed that by increasing polymer thickness the current decreases and the highest value was for the thinnest polymer layer. I-t test confirmed I-V value as the 100uL polymer has the highest current value in comparison to the other volumes. To show the Pt thickness effect, a 100uL of the polymer was spin coated on different Pt thicknesses and the highest current value was noticed for the 30nm while 5, 40, 50nm have low current. The proposed device consists of three interfaces between organic-semiconductor, semiconductor-metal, metal-semiconductor. The first interface between the metal-semiconductor in our case is Pt-N-silicon, this interface is a pure schottky diode. Moreover, the interface between the graphene and the platinum causes p-doping for the graphene and shifting the fermi-level downwards because of the Phys-sorption interaction between graphene layers and the thin film of Pt and result in increasing the number of holes in the structure. Finally, by adding PEDOT on the surface, increased p-doping level and by increasing polymer thickness the p-doping increases and will decrease current value. On the other hand, by increasing Pt-thickness, the higher the probability of graphene growth. Significant enhancement in the dark current from 99 µA for the bare graphene-Schottky devices to 20 mA for the PEDOT composite structures at −10V bias which corresponds to more than 196 times enhancement in current. The current response was extensively increased upon the deposition of PEDOT reaching 4.7 mA for the 100 µl PEDOT volume. The proposed device has shown consistency and enhancement in the current values and it could target flexible and stretchable devices.