title: Nanocarbon-based photovoltaics.
abstract: Carbon materials are excellent candidates for photovoltaic solar cells: they are Earth-abundant, possess high optical absorption, and maintain superior thermal and photostability. Here we report on solar cells with active layers made solely of carbon nanomaterials that present the same advantages of conjugated polymer-based solar cells, namely, solution processable, potentially flexible, and chemically tunable, but with increased photostability and the possibility to revert photodegradation. The device active layer composition is optimized using ab initio density functional theory calculations to predict type-II band alignment and Schottky barrier formation. The best device fabricated is composed of PC(70)BM fullerene, semiconducting single-walled carbon nanotubes, and reduced graphene oxide. This active-layer composition achieves a power conversion efficiency of 1.3%-a record for solar cells based on carbon as the active material-and we calculate efficiency limits of up to 13% for the devices fabricated in this work, comparable to those predicted for polymer solar cells employing PCBM as the acceptor. There is great promise for improving carbon-based solar cells considering the novelty of this type of device, the high photostability, and the availability of a large number of carbon materials with yet untapped potential for photovoltaics. Our results indicate a new strategy for efficient carbon-based, solution-processable, thin film, photostable solar cells.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Bernardi
authors.forename: Jessica
authors.initials: J
authors.lastname: Lohrman
authors.forename: Priyank V
authors.initials: PV
authors.lastname: Kumar
authors.forename: Alec
authors.initials: A
authors.lastname: Kirkeminde
authors.forename: Nicola
authors.initials: N
authors.lastname: Ferralis
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Grossman
authors.forename: Shenqiang
authors.initials: S
authors.lastname: Ren
mesh_terms: D011211:Electric Power Supplies; D004867:Equipment Design; D019544:Equipment Failure Analysis; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012993:Solar Energy
chemical_list: D037742:Nanotubes, Carbon