2D　perovskite　materials　are　ideal　candidates　for　indoor　photovoltaic　(IPV)　applications　due　to　their　tunable　bandgap,　high　absorption　coefficients,　and　enhanced　stability.　However,　attaining　uniform　crystallization　and　overcoming　low　carrier　mobility　remain　key　challenges　for　2D　perovskites,　limiting　their　overall　performance.　In　this　study,　a　2D　perovskite　light-absorbing　layer　is　constructed　using　a　Dion-Jacobson　(DJ)-phase　EDA(FA)(4)Pb5I16　(n　=　5)　and　introduced　butylammonium　iodide　(BAI)　for　interface　modification,　thereby　creating　a　novel　DJ/Ruddlesden-Popper　(RP)　dual　2D　perovskite　heterostructure.　By　adjusting　the　thickness　of　the　BAI-based　perovskite　layer,　the　relationship　between　interfacial　defect　states　and　carrier　mobility　is　investigated　under　varying　indoor　light　intensities.　The　results　indicate　that,　by　achieving　a　balance　between　interfacial　defect　passivation　and　carrier　transport,　the　optimized　2D　perovskite　device　reaches　a　power　conversion　efficiency　(PCE)　of　30.30%　and　an　open-circuit　voltage　(V-OC)　of　936　mV　under　1000　lux　(3000　K　LED).　2D-DJ/RP　perovskite　IPV　exhibits　a　twentyfold　increase　in　T-90　lifetime　compared　to　3D　perovskite　devices.　It　is　the　first　time　to　systematically　study　2D　perovskites　in　IPV　applications,　demonstrating　that　rationally　designed　and　optimized　2D　perovskites　hold　significant　potential　for　fabricating　high-performance　indoor　PSCs.