Applications of Optically Activated Graphene for Optoelectronic Devices
Po-Hsun Ho1*, Ya-Ping Chiu2, Wei-Hua Wang3, Chun-Wei Chen1
1Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan
2Department of Physics, National Taiwan Normal University, Taipei, Taiwan
3Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
* presenting author:Po-Hsun Ho,
Owing to the atomic-thick layer property of graphene, the electronic properties of graphene can be easily tuned with chemical doping either on the top or at the bottom surface of graphene. Although many chemical dopants have been proven to be effective in controlling transport properties of graphene, the doping level is usually approximately controlled with the concentration or thickness of dopants, making it difficult to be used in real electronic circuit.
In previous work, titanium suboxide (TiOx) was found to be a stable n-type dopant for graphene. Similar to the other dopants, the doping level was approximately tuned with different concentration of TiOx, making it impractical for real use in electronic circuits. Therefore, we tried to figure out another method to control the doping level. Because there is a preferred band alignment for electrons transferring from TiOx toward graphene, we predicted that the photoexcited electrons in TiOx would spontaneously transfer toward graphene and contribute to photoinduced doping. We successfully discovered a giant amount of photoinduced charge transfer effect in graphene/TiOx heterostructure, which can precisely control the doping to ultra-high level with various dose of incident light. Consequently, owing to precise control doping with light-sensitized graphene/TiOx heterostructure, this heterostructure has many applications in optoelectronic devices such as phototransistors, light-sensitized doping platforms, and photoactive transparent electrodes. The main emphasis in this study consists of photoinduced doping mechanism of graphene/TiOx heterostructure and its application for graphene-based optoelectronic devices.

Keywords: Graphene heterostructure, Titanium suboxide, Photoinduced doping, Photoactive electrodes, Two-dimensional materials