Singlet fission and exciton dynamics in vapor deposited rubrene films

In rubrene single crystals, singlet excitons can efficiently transition into two independent triplet excitons through a process called singlet fission. Photoluminescence in single crystals is a result of the singlet exciton’s radiative decay and both geminate and non-geminate triplet pair recombination. This process has been well documented, although a precise description of the intermediate steps is still an active area of research. In more disordered systems, such as amorphous films of rubrene, the singlet fission process is greatly hindered and the likelihood of non-geminate triplet recombination is effectively zero. As a result, photoluminescence measurements show only the radiative decay of the singlet exciton, as no singlet fission can occur. The effect of molecular ordering and the photoluminescence dynamics of amorphous rubrene samples will be addressed.