Bias-induced photoluminescence quenching of single colloidal quantum dots embedded in organic semiconductors

Publication Type:

Journal Article

Source:

Nano Lett., ACS Publications, Volume 7, Issue 12, p.3781-3786 (2007)

ISBN:

1530-6984

Keywords:

2007, 2013 and earlier

Abstract:

We demonstrate reversible quenching of the photoluminescence from single CdSe/ZnS colloidal quantum dots embedded in thin films of the molecular
organic semiconductor
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD)
in a layered device structure. Our analysis, based on current and charge
carrier density, points toward field ionization as the dominant
photoluminescence quenching mechanism. Blinking traces from individual
quantum dots reveal that the photoluminescence amplitude decreases
continuously as a function of increasing forward bias even at the single
quantum dot level. In addition, we show that quantum dot photoluminescence
is quenched by aluminum tris(8-hydroxyquinoline) (Alq3) in chloroform
solutions as well as in thin solid films of Alq3 whereas TPD has little
effect. This highlights the importance of chemical compatibility between
semiconductor nanocrystals and surrounding organic semiconductors. Our
study helps elucidate elementary interactions between quantum dots and
organic semiconductors, knowledge needed for designing efficient quantum
dot organic optoelectronic devices.