Temperature dependence of photoluminescence in polyfluorene thin films—Huang–Rhys factors of as-coated, annealed and crystallized thin films

The temperature dependences of photoluminescense of poly(9,9-dioctylfluorene) (F8) thin films with three different backbone conformations controlled by thermal treatments, such as as-coated, annealed and crystallized thin films have been studied. The polymer forms disordered phase in the as-coated film, and ordered phase in the crystallized film. It is found that the strength of electron–phonon interaction, which is evaluated from Huang–Rhys factors, is enhanced with increasing temperature in all the films. The film annealed at around glass-transition temperature shows stronger temperature dependence of Huang–Rhys factor, suggesting that the annealed film consists of different phases such as disordered and β-phase.