Issue 7, 2016

Ligand enhanced upconversion of near-infrared photons with nanocrystal light absorbers

Abstract

We designed and synthesized a tetracene derivative 4-(tetracen-5-yl)benzoic acid (CPT) as a transmitter ligand used in PbS/PbSe nanocrystal (NC) sensitized upconversion of near infrared (NIR) photons. Under optimal conditions, comparing CPT functionalized NCs with unfunctionalized NCs as sensitizers, the upconversion quantum yield (QY) was enhanced 81 times for 2.9 nm PbS NCs from 0.021% to 1.7%, and 11 times for 2.5 nm PbSe NCs from 0.20% to 2.1%. The surface density of CPT controls the solubility of functionalized NCs and the upconversion QY. By increasing the concentration of CPT in the ligand exchange solution, the number of CPT ligand per NC increases. The upconversion QY is maximized at a transmitter density of 1.2 nm−2 for 2.9 nm PbS, and 0.32 nm−2 for 2.5 nm PbSe. Additional transmitter ligands inhibit photon upconversion due to triplet–triplet annihilation (TTA) between two neighboring CPT molecules on the NC surface. 2.1% is the highest reported QY for TTA-based photon upconversion in the NIR with the use of earth-abundant materials.

Graphical abstract: Ligand enhanced upconversion of near-infrared photons with nanocrystal light absorbers

Supplementary files

Article information

Article type
Edge Article
Submitted
19 Jan 2016
Accepted
02 Mar 2016
First published
04 Mar 2016
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2016,7, 4101-4104

Ligand enhanced upconversion of near-infrared photons with nanocrystal light absorbers

Z. Huang, D. E. Simpson, M. Mahboub, X. Li and M. L. Tang, Chem. Sci., 2016, 7, 4101 DOI: 10.1039/C6SC00257A

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