In this manuscript, non-classical nonvertical triplet acceptors are proposed as a promising class of efficient triplet
scavengers for future solid-state electrically pumped organic lasers. Triplet excitation scavenging is investigated in
polymer films of polyfluorene, a prospective material for the fabrication of thin-film organic lasers. Two dopant
molecules, cyclooctatetraene (COT, a nonvertical triplet acceptor) and anthracene (a vertical triplet acceptor), are studied
and the occurrence of anomalous nonvertical triplet energy transfer in solid conjugated polymer films is demonstrated for
the first time employing COT.
In this manuscript, we report on the performance of organic light-emitting diodes with remote metallic contact using
N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C<sub>13</sub>H<sub>27</sub>) as well as perfluorohexyl-sustituted
quaterthiophenes (DHF-4T) as the electron-transport material. Both materials exhibit high electron field-effect mobility.
An electron mobility of 0.123 cm<sup>2</sup>/Vs is demonstrated for DHF-4T. The wide optical bandgap of DHF-4T allows
reduction of the light absorption in the region of interest compared to PTCDI-C<sub>13</sub>H<sub>27</sub>. In this way an external
quantum efficiency of 0.25% could be obtained. This is a factor of 10 larger than in PTCDI-C<sub>13</sub>H<sub>27</sub> based devices.
We have realized an organic two-contact, light-emitting device with reduced exciton quenching and photon absorption at
the metal cathode. Compared to a conventional organic light-emitting diode (OLED), the metal cathode is displaced by
one to several microns from the light-emission zone. Electron transport between the cathode and the light-emission zone
occurs by field-effect, and hence with an enhanced mobility compared to electron transport in a conventional OLED. The
electrical characteristics and the opto-electronic performance of this light-emitting device are measured. Numerical
simulations indicate that the electronic and excitonic characteristics are in good agreement with these measurements.
Maximum singlet densities comparable to those in OLEDs can be achieved, while optical and excitonic losses are
reduced. This might possibly result in optical gain.
We have realized a light-emitting organic field-effect transistor (LEOFET). Excitons are generated at the interface
of an n-type and a p-type organic semiconductor heterostructure inside the transistor channel. The dimensions
and the position of the p-n heterostructure are defined by photolithography. The recombination region is several
microns from the metal electrodes. Therefore, the exciton quenching probability in this device is reduced.
Numerical simulations show that the recombination region can move within the transistor channel by changing
the biasing conditions.