Organic-inorganic　hybrid　lead　perovskite　films　are　crucial　in　perovskite　solar　cells　(PSCs).　However,　a　solution　deposition　process　rendered　a　polycrystalline　feature　to　perovskite　films　with　a　large　number　of　ionic　defects　on　the　surface　and　grain　boundaries,　which　will　serve　as　non-radiative　recombination　centers,　limiting　the　photovoltaic　performance　of　PSCs.　In　this　work,　D-A-π-A-type　organic　sensitizers　(MM-3　and　MM-4)　with　a　quinoxaline　moiety　were　employed　to　enhance　light　harvesting　and　reduce　the　trap　states　of　perovskite　films.　MM-4　of　the　D-A-π-A　system　dye　has　a　more　coplanar　structure　because　it　contains　a　thiophene　π-bridging　moiety,　which　would　facilitate　electron　transfer　in　molecules,　enrich　electron　density　on　the　terminal　carboxyl　group　and　provide　good　condition　for　coordination　with　undercoordinated　Pb2+,　resulting　in　the　reduction　of　trap　states　and　suppression　of　the　non-radiative　recombination　in　perovskite　films.　Therefore,　there　was　a　significant　increase　in　the　open-circuit　voltage　(VOC)　from　1.02　to　1.08　V,　and　PCE　increased　from　18.91%　to　20.31%.　Furthermore,　the　long　alkyl　chains　will　enhance　the　hydrophobicity　of　perovskite　films,　and　PSCs　passivated　by　MM-4　exhibited　excellent　stability　without　encapsulation.　It　can　maintain　about　92%　of　initial　PCE　under　15　±　5%　relative　humidity　after　70　days　and　over　77%　of　initial　PCE　under　50-60%　relative　humidity　after　550　h.　We　demonstrate　that　the　D-A-π-A　sensitizer　can　be　another　passivator　for　effectively　passivating　the　trap　states,　which　significantly　improve　the　PCE　and　device　durability.　This　journal　is　©　The　Royal　Society　of　Chemistry.