Harnessing fluorescence versus phosphorescence branching ratio in (Phenyl)n-bridged (n = 0-5) bimetallic Au(I) complexes
Journal
Journal of Physical Chemistry C
Journal Volume
117
Journal Issue
19
Pages
9623-9632
Date Issued
2013
Author(s)
Chang, Y.-C.
Tang, K.-C.
Pan, H.-A.
Liu, S.-H.
Koshevoy, I.O.
Karttunen, A.J.
Hung, W.-Y.
Cheng, M.-H.
Abstract
We have designed and synthesized a series of Au(I) complexes bearing either an alkynyl–(phenylene)n–diphosphine (A-0–A-3) or a (phenylene)n–diphosphine (B-1–B-5) bridge, among which the effective distance between Au(I) and the center of the emitting ππ* chromophore can be fine-tuned via the insertion of various numbers of phenylene spacers. We then demonstrated for the first time in a systematic manner the decrease of rate constant for S1 → T1 intersystem crossing (ISC) kisc as the increase of the effective distance. The results also unambiguously showed that the phosphorescence could be harvested via higher S0 → Sn (n > 1) electronic excitation, followed by fast Sn → Tm ISC and then the population at T1 state, bypassing the relatively slow S1 → T1 ISC. The results unify a recent report on higher excited-state relaxation dynamics for the late transition metal complexes (J. Am. Chem. Soc.2012, 134, 7715–7724). The dual, far separated fluorescence and phosphorescence of the titled complexes make feasible the white light generation in a single molecule unit, as successfully demonstrated using complex B-3 as a dopant to fabricate organic light emitting diodes.
Type
journal article