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Proceedings Paper

Resonant coupling for light trapping in colloidal quantum dot photovoltaics (Conference Presentation)
Author(s): Fiona Beck; Gerasimos Konstantatos
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Paper Abstract

Lead based colloidal quantum dots (CQDs) are a promising optoelectronic material system for solar harvesting, as the excitonic peak can be tuned from the visible to the near infra-red. These materials can be manufactured in the solution phase and spin-cast to form dense, cross-linked, semiconductor films on a variety of substrates, reducing the cost of device fabrication. However, like other non-crystalline based semiconductors, these films exhibit short carrier lifetimes and diffusion lengths. Active layers must be kept very thin to ensure efficient extraction of the photogenerated carriers, and device efficiencies will ultimately be limited by absorption. In this work we present a conceptual model of light trapping by resonant mode coupling in thin, mode limited devices. We show that targeting certain guided modes results in larger overall absorption, resulting in two key insights: 1) that a large spatial overlap of the mode profile with the grating is important; and 2) CQD materials have favourable material constants to benefit from absorption in the near-field of plasmonic resonances. Photocurrent enhancements of up to 250% at the exciton peak are achieved by coupling to optimal guided modes, compared with an increase of 25% in the same wavelength region for coupling to non-optimal modes. This result demonstrates that insights gained from an understanding of the mode profile of low mode density optoelectronics can be leveraged to provide tuneable light trapping and dramatically increase the absorption enhancement.

Paper Details

Date Published: 18 September 2018
Proc. SPIE 10759, New Concepts in Solar and Thermal Radiation Conversion and Reliability, 1075910 (18 September 2018); doi: 10.1117/12.2322889
Show Author Affiliations
Fiona Beck, The Australian National Univ. (Australia)
Gerasimos Konstantatos, ICFO - Institut de Ciències Fotòniques (Spain)

Published in SPIE Proceedings Vol. 10759:
New Concepts in Solar and Thermal Radiation Conversion and Reliability
Jeremy N. Munday; Peter Bermel; Michael D. Kempe, Editor(s)

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