We investigate the properties of long-lived species in F8BT films through time-resolved photoluminescence (PL) measurements at room temperature and 10 K. The kinetics consist of an initial exponential decay (τ = 2.26 ns) followed by a weak power-law decay (I(t) ∝ t–1) up to at least 1 ms, both of which depend weakly on temperature. From fluence-dependent PL and ultrafast transient absorption (TA) measurements, we confirm that this emission arises from the recombination of geminate charge-pairs generated through singlet–singlet annihilation. This behavior is a consequence of the donor–acceptor nature of this polymer, which enhances singlet–singlet annihilation and facilitates the formation of long-lived geminate-pairs from energetic singlet states.
American Chemical Society
25 Apr 2013
Volume: 117 Issue: 16 Pages: 4649-4653
The Journal of Physical Chemistry B