Picosecond time‐resolved luminescence of tetracene thin films

The energy relaxation of excitons in the organic semiconductor tetracene (film thickness 160 nm) is studied by photoluminescence from 15 to 300 K using time‐correlated single‐photon counting. The well‐known relaxation of triplet excitons with time constant ∼7 ns is accompanied by a faster relaxation process with time constants ranging from 260 ps to 1.2 ns, depending on temperature and wavelength.