title: Effect of Chloride Passivation on Recombination Dynamics in CdTe Colloidal Quantum Dots.
abstract: Colloidal quantum dots (CQDs) can be used in conjunction with organic charge-transporting layers to produce light-emitting diodes, solar cells and other devices. The efficacy of CQDs in these applications is reduced by the non-radiative recombination associated with surface traps. Here we investigate the effect on the recombination dynamics in CdTe CQDs of the passivation of these surface traps by chloride ions. Radiative recombination dominates in these passivated CQDs, with the radiative lifetime scaling linearly with CQD volume over τr =20-55 ns. Before chloride passivation or after exposure to air, two non-radiative components are also observed in the recombination transients, with sample-dependent lifetimes typically of less than 1 ns and a few ns. The non-radiative dynamics can be explained by Auger-mediated trapping of holes and the lifetimes of this process calculated by an atomistic model are in agreement with experimental values if assuming surface oxidation of the CQDs.
authors: School of Physics and Astronomy and Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL (UK).
authors: Daniel
authors: D
authors: Espinobarro-Velazquez
authors: Marina A
authors: MA
authors: Leontiadou
authors: Robert C
authors: RC
authors: Page
authors: Marco
authors: M
authors: Califano
authors: Paul
authors: P
authors: O'Brien
authors: David J
authors: DJ
authors: Binks
keywords: chloride; nanoparticles; passivation; photoluminescence; quantum dots
references: Nat Mater. 2014 Aug;13(8):796-801
references: 24859641
references: Nat Nanotechnol. 2012 Sep;7(9):577-82
references: 22842552
references: J Phys Chem Lett. 2013 May 2;4(9):1519-25
references: 26282308
references: Phys Rev Lett. 2005 Dec 2;95(23):236804
references: 16384329
references: Nano Lett. 2014 Mar 12;14(3):1263-9
references: 24359156
references: ACS Nano. 2013 Jun 25;7(6):5282-90
references: 23701285
references: Adv Mater. 2014 Feb 12;26(6):937-42
references: 24243769
references: Nano Lett. 2012 Sep 12;12(9):4508-17
references: 22849432
references: Nat Mater. 2013 May;12(5):445-51
references: 23377294
references: Nat Nanotechnol. 2010 Jun;5(6):391-400
references: 20473301
references: Nat Mater. 2014 Aug;13(8):822-8
references: 24907929
references: Nature. 2011 Nov 09;479(7372):203-7
references: 22071764
references: J Phys Chem Lett. 2013 Mar 21;4(6):908-18
references: 26291355
references: Chemphyschem. 2009 Mar 9;10(4):680-5
references: 19137566
references: Small. 2015 Apr;11(13):1548-54
references: 25348200
references: Chem Sci. 2012 Jun 1;3(6):2028-2034
references: 24932403
references: Nano Lett. 2013 May 8;13(5):2047-52
references: 23627433
references: J Am Chem Soc. 2012 Dec 12;134(49):20160-8
references: 23131125