This paper presents preliminary synthetic and physical study of a new polythiophene block copolymer. These are conjugated donor (D) block poly(hexylenedithiathiophene) copolymerized with an acceptor (A) block of fluorinated ester derivatized polythiophene via an aliphatic bridge (B) unit. Experimental results show that when -DBAB- type of block copolymer forms, there is strong photoluminescence (PL) quenching in -DBAB- relative to D/A blend or the pristine D or A blocks. PL quenching is attributed to both intra and inter chain photo induced electron transfer or charge separation. Since block copolymer can be easily tailored, this system appears attractive for light harvesting applications including photovoltaic applications.