Hole and Electron Extraction Layers Based on Graphene Oxide Derivatives for High-Performance Bulk Heterojunction Solar Cells
Abstract
Graphene, having a single-atom-thick sheet of carbon atoms packed in a 2D honeycomb lattices, possesses excellent electronic, thermal, and mechanical properties attractive for a large variety of potential applications, including transparent electrodes and/or active materials in electronic devices, solar cells, supercapacitors, batteries, fuel cells, actuators, and sensors. Graphene has also been found to be useful as the platform of biomedical sensors. The recent availability of solution processable graphene by exfoliation of graphite into graphene oxides (GOs), followed by solution reduction, has allowed the functionalization, characterization, and processing of graphene sheets via various solution methods. It has been demonstrated that GO consists of epoxy and hydroxyl groups on the basal plane and carboxylic groups at the edge. The C O bonds on the basal plane disrupt the conjugation of the hexagonal graphene lattice to render GO insulator or semiconductor. Due to strong interactions between the hexagonally sp 2 -bonded carbon layers in graphite, the solution oxidation of graphite requires strong oxidizing reagents (e.g., HNO 3 , KMnO 4 , and/ or H 2 SO 4 ) under harsh conditions. This often leads to severe damage to the carbon basal plane, and hence a poorly defi ned electronic structure. It remains a big challenge to design GO-based materials with controlled electronic properties for high-performance device applications. Further to our work on functionalization of graphene (oxide), we have recently found that simple charge neutralization of the COOH groups in GO with Cs 2 CO 3 could tune the electronic structure of GO, making GO derivatives useful as both hole- and electron-extraction layers in bulk heterojunction (BHJ) solar cells.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2012
- Accession Number
- ADA578742
Entities
People
- Dingshan Yu
- Jun Liu
- Liming Dai
- Michael Durstock
- Yuhua Xue
- Yunxiang Gao
Organizations
- Air Force Research Laboratory