D-pi-A　type　4-((9-phenylcarbazol-3-yl)ethynyl)-N-dodecyl-1,8-naphthalimide　(CZNI)　with　a　large　dipole　moment　of　8.49　D　and　A-pi-A　type　bis[(4,4　＇-1,8-naphthalimide)-N-dodecyl]ethyne　(NINI)　with　a　negligible　dipole　moment　of　0.28　D,　were　smartly　designed　and　synthesized　to　demonstrate　the　evidence　of　a　molecular　dipole　as　the　dominant　mechanism　for　controlling　charge　separation　of　organic　semiconductors.　In　aqueous　solution,　these　two　novel　naphthalimides　can　self-assemble　to　form　nanoribbons　(NRs)　that　present　significantly　different　traces　of　exciton　dissociation　dynamics.　Upon　photoexcitation　of　NINI-NRs,　no　charge-separated　excitons　(CSEs)　are　formed　due　to　the　large　exciton　binding　energy,　accordingly　there　is　no　hydrogen　evolution.　On　the　contrary,　in　the　photoexcited　CZNI-NRs,　the　initial　bound　Frenkel　excitons　are　dissociated　to　long-lived　CSEs　after　undergoing　ultrafast　charge　transfer　within　ca.　1.25　ps　and　charge　separation　within　less　than　5.0　ps.　Finally,　these　free　electrons　were　injected　into　Pt　co-catalysts　for　reducing　protons　to　H-2　at　a　rate　of　ca.　417　mu　mol　h(-1)　g(-1),　correspondingly　an　apparent　quantum　efficiency　of　ca.　1.3　%　can　be　achieved　at　400　nm.