title: Graphene-Based Integrated Photovoltaic Energy Harvesting/Storage Device.
abstract: Energy scavenging has become a fundamental part of ubiquitous sensor networks. Of all the scavenging technologies, solar has the highest power density available. However, the energy source is erratic. Integrating energy conversion and storage devices is a viable route to obtain self-powered electronic systems which have long-term maintenance-free operation. In this work, we demonstrate an integrated-power-sheet, consisting of a string of series connected organic photovoltaic cells (OPCs) and graphene supercapacitors on a single substrate, using graphene as a common platform. This results in lighter and more flexible power packs. Graphene is used in different forms and qualities for different functions. Chemical vapor deposition grown high quality graphene is used as a transparent conductor, while solution exfoliated graphene pastes are used as supercapacitor electrodes. Solution-based coating techniques are used to deposit the separate components onto a single substrate, making the process compatible with roll-to-roll manufacture. Eight series connected OPCs based on poly(3-hexylthiophene)(P3HT):phenyl-C61-butyric acid methyl ester (PC60 BM) bulk-heterojunction cells with aluminum electrodes, resulting in a ≈5 V open-circuit voltage, provide the energy harvesting capability. Supercapacitors based on graphene ink with ≈2.5 mF cm(-2) capacitance provide the energy storage capability. The integrated-power-sheet with photovoltaic (PV) energy harvesting and storage functions had a mass of 0.35 g plus the substrate.
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK.
authors.forename: Chih-Tao
authors.initials: CT
authors.lastname: Chien
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK.
authors.forename: Pritesh
authors.initials: P
authors.lastname: Hiralal
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, 106, Taiwan.|Institute of Atomic and Molecular Sciences Academia Sinica, Taipei, 106, Taiwan.
authors.forename: Di-Yan
authors.initials: DY
authors.lastname: Wang
authors.affiliation: Department of Chemistry, National Taiwan Normal University, Taipei, 116, Taiwan.
authors.forename: I-Sheng
authors.initials: IS
authors.lastname: Huang
authors.affiliation: Institute of Atomic and Molecular Sciences Academia Sinica, Taipei, 106, Taiwan.|Department of Chemistry, National Taiwan Normal University, Taipei, 116, Taiwan.
authors.forename: Chia-Chun
authors.initials: CC
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, 106, Taiwan.
authors.forename: Chun-Wei
authors.initials: CW
authors.lastname: Chen
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK.
authors.forename: Gehan A J
authors.initials: GA
authors.lastname: Amaratunga
keywords: graphene; integrated-power-sheet; organic photovoltaics; self-powered; supercapacitors