Photoluminescence dynamics of thiophene/phenylene co-oligomer thin films based on Förster energy transfer

Photoluminescence dynamics based on Förster energy transfer between 2,5-bis(4-biphenylyl)thiophene (BP1T) and 5,5ʺʺ′-diphenyl-2,2′:5′,2ʺ:5ʺ,2ʺ′:5ʺ′,2ʺʺ:5ʺʺ,2ʺʺ′-sexithiophene (P6T) were investigated for their co-evaporated and laminated thin films. In the former film, the blue fluorescence of the BP1T donor was thoroughly quenched by 0.06 mol% of the P6T acceptor based on the Förster energy transfer, resulting in white luminescence. From time-decay measurements of the donor fluorescence, the Förster radius was determined to be 3.4-3.9 nm. The laminated films were fabricated by successive depositions of BP1T, MgF2 and P6T in which the thickness of the MgF2 spacer was varied. The energy transfer from the BP1T to P6T layer was controlled by the MgF2 thickness.