Spectroscopic and morphological studies on a series of rod-coil block copolymers containing terfluorene segments as the rigid blocks and polystyrene as the flexible parts demonstrate an increase in the photoluminescence intensity and the exciton lifetime as well as formation of isolated spheres as thin films upon thermal annealing in air (200 degrees C for 30 min). Moreover, no appearance of the low energy emission band centered at 520 nm was found after the same thermal treatment which permits these copolymers to emit pure blue light.