Excitonic Effects in Emerging Photovoltaic Materials: A Case Study in Cu_2O
Abstract
Excitonic effects account for a fundamental photoconversion and charge transport mechanism in Cu_2O; hence, the universally adopted "free carrier" model substantially underestimates the photovoltaic efficiency for such devices. The quasi-equilibrium branching ratio between excitons and free carriers in Cu_2O indicates that up to 28% of photogenerated carriers during photovoltaic operation are excitons. These large exciton densities were directly observed in photoluminescence and spectral response measurements. The results of a device physics simulation using a model that includes excitonic effects agree well with experimentally measured current–voltage characteristics of Cu_2O-based photovoltaics. In the case of Cu_2O, the free carrier model underestimates the efficiency of a Cu_2O solar cell by as much as 1.9 absolute percent at room temperature.
Additional Information
© 2017 American Chemical Society. Received: December 19, 2016; Accepted: January 19, 2017; Published: January 19, 2017. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. Y.T. and H.A.A. are supported by the Dow Chemical Company under the earth-abundant semiconductor project. S.T.O. thanks S. Yalamanchili, K. Sun, and A. Carim for helpful discussions. The authors declare no competing financial interest.Attached Files
Supplemental Material - nz6b00704_si_001.pdf
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Additional details
- Eprint ID
- 73753
- Resolver ID
- CaltechAUTHORS:20170126-105722527
- Department of Energy (DOE)
- DE-SC0004993
- Dow Chemical Company
- Created
-
2017-01-26Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field
- Caltech groups
- JCAP, Kavli Nanoscience Institute