Enhanced emission from acceptor in the annealed film of all-conjugated diblock copolymer

The optical properties of a new diblock copolymer poly(2,5-dioctyloxy-p-phenylene)-block-poly(3-methoxyethoxyethoxymethylthiophene) (PPP-b-P3MEEMT) have been investigated by comparison with the pristine and annealed films. The two blocks in the copolymer can crystallize to form lamellas in nanoscale during thermal annealing, which have been characterized by X-ray diffraction (XRD) spectrum and transmission electron microscopy (TEM). The emission intensities of the PPP and P3MEEMT blocks in the annealed copolymer film are both increased relative to those in the pristine copolymer film. The resonance energy transfer from the PPP blocks to the P3MEEMT blocks occurs in the film since the absorption of the P3MEEMT block partially overlaps with the emission from the PPP block. The enhanced emission from the P3MEEMT block has been observed in the annealed copolymer film due to the efficient resonance energy transfer and high fluorescence efficiency of the P3MEEMT blocks in the ordered nanostructures.