a — donor - bridge - acceptor - bridge — type block copolymer system , where donor is an organic conjugated donor block , acceptor is an organic conjugated acceptor block , and bridge is a non - conjugated and flexible chain , has been designed and preliminarily tested for potential lightweight , flexible shape , cost - effective and high efficiency “ plastic ” thin film solar cell or photo detector applications . a ‘ tertiary supramolecular nanophase separated structure ” derived from this — dbab — block copolymer improves opto - electronic power conversion efficiency significantly in comparison to all existing reported organic or polymeric donor / acceptor binary photovoltaic systems due to the reduction of “ exciton loss ,” the “ carrier loss ,” as well as the “ photon loss ” via three - dimensional space and energy level optimizations .