We report the synthesis of a series of block copolymers consisting of a rod‐like semiconducting poly(2,5‐di(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene) (DEH‐PPV) block and a flexible poly(lactic acid) (PLA) block that can be selectively degraded under mild conditions. Such selectively degradable block copolymers are designed as self‐assembling templates for bulk heterojunction donor–acceptor layers in organic solar cells. A lamellar microphase‐separated domain structure was identified for block copolymers with PLA volume fractions between 29 and 79% in bulk and thin films using SAXS, TEM, and AFM. Depending on the ratio of the two blocks we find either lamellae oriented parallel or perpendicular to the substrate in thin films.
