Efficiency enhancement of organic thin-film phototransistors due to photoassisted charge injection

Understanding the underlying physics of charge transport in organic semiconductors under illumination is important for the development of novel optoelectronic applications. We study the effects of monochromatic light in the visible spectrum on the channel of an organic thin-film transistor based on...

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Bibliographic Details
Published in:Applied physics letters 2021-08, Vol.119 (7)
Main Authors: Jagoo, Zafrullah, Lamport, Zachary A., Jurchescu, Oana D., McNeil, L. E.
Format: Article
Language:English
Subjects:
Applied physics
Charge efficiency
Charge injection
Charge transport
Current carriers
Excitons
Optoelectronics
Organic semiconductors
Photon absorption
Photons
Phototransistors
Potential barriers
Semiconductor devices
Thin film transistors
Transistors
Visible spectrum
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Summary:Understanding the underlying physics of charge transport in organic semiconductors under illumination is important for the development of novel optoelectronic applications. We study the effects of monochromatic light in the visible spectrum on the channel of an organic thin-film transistor based on 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene. When the channel of the transistor was illuminated with red, green, or blue light, more charge carriers were measured than what exciton generation from photon absorption alone could provide, leading to a photon-to-charge-carrier conversion efficiency much larger than 100%. We explain this phenomenon using a model incorporating space-charge limited photocharges and enhanced hole injection from the source electrode due to lowering of the potential barrier by photogenerated electrons.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0047570