Quantum Dot Photovoltaics in the Extreme Quantum Confinement Regime: The Surface-Chemical Origins of Exceptional Air- and Light-Stability

Jiang Tang, Lukasz Brzozowski, D. Aaron R. Barkhouse, Xihua Wang, Ratan Debnath, Remigiusz Wolowiec, Elenita Palmiano, Larissa Levina, Andras G. Pattantyus-Abraham, Damir Jamakosmanovic, Edward H. Sargent

Research output: Contribution to journalArticlepeer-review

282 Scopus citations

Abstract

We report colloidal quantum dot (CQDs) photovoltaics having a ∼930 nm bandgap. The devices exhibit AM1.5G power conversion efficiencies in excess of 2%. Remarkably, the devices are stable in air under many tens of hours of solar illumination without the need for encapsulation. We explore herein the origins of this ordersof-magnitude improvement in air stability compared to larger PbS dots. We find that small and large dots form dramatically different oxidation products, with small dots forming lead sulfite primarily and large dots, lead sulfate. The lead sulfite produced on small dots results in shallow electron traps that are compatible with excellent device performance; whereas the sulfates formed on large dots lead to deep traps, midgap recombination, and consequent catastrophic loss of performance. We propose and offer evidence in support of an explanation based on the high rate of oxidation of sulfur-rich surfaces preponderant in highly faceted large-diameter PbS colloidal quantum dots. © 2010 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)869-878
Number of pages10
JournalACS Nano
Volume4
Issue number2
DOIs
StatePublished - Jan 27 2010
Externally publishedYes

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