Supplemental
Title: Highly efficient tris-(8-hydroxyquinoline) aluminum based organic light-
emitting diodes utilized by balanced energy transfer with co-sensitizing
fluorescent dyes
Journal: Applied Physics Letters
Authors: Young Wook Park, Young Min Kim, Jin Hwan Choi, Tae Hyun Park,
Jin Woo Huh, Hong Suk Kim, Min Ju Cho, Dong Hoon Choi, and
Byeong Kwon Ju
<Clarify the multiple emissive dopants: TRES measurement>
For clarity of multiple emission of multiple dopants in graded configuration, the photoluminescence
TRES of co-doped thin films were performed. Fig. s-1 shows the time resolved emission spectra with
differing co-doping profiles.
Fig s- 1. The photoluminescence time resolved emission spectroscopy spectra of co-doped
Alq3 thin films. The doping concentrations were varied to correlate the energy transfer and
doping concentration; (left) C545T:DMQA (1.0:0.5 %) doped Alq 3, (center) C545T:DMQA
(1.0:1.0 %) doped Alq3, (right) and C545T:DMQA (1.5:1.5 %) doped Alq 3. Three spectra were
taken from the time scale slicing the RAW TRES spectra. ‘Prompt’ spectra were taken at the
peak fluorescence intensity at decay spectra which is 5.9ns after the excitation. ‘Delayed’
means the fluorescent spectra ‘x ns’ delayed after the ‘prompt’.
Comparing the 1.0:0.5% - 1.0:1.0% - 1.5:1.5% doped thin films, it is seen that the energy transfer to
DMQA becomes much faster. In the 1.0:0.5 wt% and 1.0:1.0 wt% doped, both the C545T and the
DMQA are emissive. On the other hand, the 1.5:1.5 wt% doped system shows the most DMQA
emissions, and also becomes weaker much faster. This result could be direct evidence* of the
realization of controlling the energy transfer distribution, in other words it is demonstrating a BICET
condition.
*J.-H. Lee, C.-C. Teng, J.-H. Lin, T.-C. Lin, and C. C. Yang, “Direct Observations of Energy Transfer
and Quenching Dynamics between Alq3 and C545T in Thin Films with Different Doping
Concentrations,” Proc. of SPIE, vol. 5632, pp. 66-71, 2005
Measurement:
The time-resolved emission spectroscopy (TRES) by time correlated single photon counting method
has been used to take time resolved emission spectra using the FLS920 Spectrometer (Edinburgh,
Instruments Ltd.).
<Supplemental of single molecular optical properties of Alq3, C545T, and DMQA>
For convenience, to prevent referring the references, basic optical properties are shown in Fig. s-2;
UV-Vis absorbance and PL intensity spectra.
Fig s- 2. UV-Vis absorbance and PL intensity of Alq3, C545T, and DMQA thin films. C545T
shows better absorption coefficient while DMQA shows better UV-PL spectral overlapping
with Alq3.