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Nano Lett. 2015 Nov 11;15(11):7691-6. doi: 10.1021/acs.nanolett.5b03677. Epub 2015 Nov 2.

High-Efficiency Colloidal Quantum Dot Photovoltaics via Robust Self-Assembled Monolayers.

Author information

1
Department of Electrical and Computer Engineering, University of Toronto , 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
2
School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, South Korea.

Abstract

The optoelectronic tunability offered by colloidal quantum dots (CQDs) is attractive for photovoltaic applications but demands proper band alignment at electrodes for efficient charge extraction at minimal cost to voltage. With this goal in mind, self-assembled monolayers (SAMs) can be used to modify interface energy levels locally. However, to be effective SAMs must be made robust to treatment using the various solvents and ligands required for to fabricate high quality CQD solids. We report robust self-assembled monolayers (R-SAMs) that enable us to increase the efficiency of CQD photovoltaics. Only by developing a process for secure anchoring of aromatic SAMs, aided by deposition of the SAMs in a water-free deposition environment, were we able to provide an interface modification that was robust against the ensuing chemical treatments needed in the fabrication of CQD solids. The energy alignment at the rectifying interface was tailored by tuning the R-SAM for optimal alignment relative to the CQD quantum-confined electron energy levels. This resulted in a CQD PV record power conversion efficiency (PCE) of 10.7% with enhanced reproducibility relative to controls.

KEYWORDS:

Quantum dot solar cells; R-SAM; dipole moment; high performance; interface; robust

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