The trouble with TOPO; identification of adventitious impurities beneficial to the growth of cadmium selenide quantum dots, rods, and wires

Fudong Wang, Rui Tang, William E. Buhro

Research output: Contribution to journalArticlepeer-review

132 Scopus citations

Abstract

Tri-n-octylphosphine oxide (TOPO) is a commonly used solvent for nanocrystal synthesis. Commercial TOPO samples contain varying amounts of phosphorus-containing impurities, some of which significantly influence nanocrystal growth. Consequently, nanocrystal syntheses often give irreproducible results with different batches of TOPO solvent. In this study, we identify TOPO impurities by 31P NMR, and correlate their presence with the outcomes of CdSe nanocrystal syntheses. We subsequently add the active impurity species, one by one, to purified TOPO to confirm their influence on nanocrystal syntheses. In this manner, di-n-octylphosphine oxide (DOPO) is shown to assist CdSe quantum-dot growth; di-n-octylphosphinic acid (DOPA) and mono-n-octylphosphinic acid (MOPA) are shown to assist CdSe quantum-rod growth, and DOPA is shown to assist CdSe quantum-wire growth. (The TOPO impurity n-octylphosphonic acid, OPA, has been previously shown to assist quantum-rod growth.) The beneficial impurities are prepared on multigram scales and can be added to recrystallized TOPO to provide reproducible synthetic results.

Original languageEnglish
Pages (from-to)3521-3524
Number of pages4
JournalNano Letters
Volume8
Issue number10
DOIs
StatePublished - Oct 1 2008

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