Photoluminescence quenching of tris-(8-hydroxyquinoline) aluminum thin films at interfaces with metal oxide films of different conductivities

Publication Type:

Journal Article

Source:

Phys. Rev. B Condens. Matter, American Physical Society, Volume 79, Issue 23, p.235205 (2009)

ISBN:

0163-1829

Keywords:

2009, 2013 and earlier

Abstract:

We report a comprehensive study of photoluminescence (PL) quenching of tris-(8-hydroxyquinoline) aluminum (Alq3) at interfaces with thin films of
tin oxide (SnO2) using both steady-state and time-resolved measurements.
Quenching of excitons generated in the Alq3 layer increased with increased
conductivity of the SnO2 films, which we relate with the presence of
nonradiative energy transfer from excitons in Alq3 to transitions in SnO2.
In addition, due to the semitransparency of SnO2, the effects of optical
interference on the steady-state PL quenching of Alq3 are determined. We
demonstrate that without accounting for the interference effects in the
excitation, the extracted exciton diffusion length (Ld) in Alq3 is in the
range of 10–20 nm. However, when using a numerical model to account for
the optical interference effects, we find that Ld is in the range of 5–9
nm, which agrees with Ld extracted from time-resolved measurements (4–6
nm). We conclude that time-resolved measurements are least affected by
optical interference, yielding the most accurate measurement of Ld.