In　photodetectors　based　on　heterojunctions　of　organic　semiconductor　and　hybrid　perovskite,　the　strong　light　absorbing　ability　of　perovskite　and　the　gate-tunability　of　organic　semiconductor　can　be　preferably　incorporated.　However,　the　charge　current　transfer　at　the　interface,　and　the　double　channel　transportation　in　the　heterojunctions　are　not　fully　understood.　The　authors　successfully　transfer　the　mechanically　exfoliated　Ruddlesden-Popper　(RP)　layered　perovskite　single　crystal　to　the　thermal　evaporated　organic　small　molecule　semiconductor　forming　a　heterojunction.　Based　on　the　heterojunction,　two　configurations　of　light　detecting　devices　are　prepared　in　which　the　perovskite　layer　acts　as　either　a　conducting　channel　and　light　absorbing　layer　or　light　absorbing　layer　only.　The　light　detecting　performance　of　such　devices　is　systematically　investigated.　The　charge　transfer　from　the　perovskite　single　crystal　to　the　organic　semiconductor　layer　is　observed　by　Kelvin　Probe　Force　Microscope　characterization.　They　also　find　that　the　n　values　of　the　RP　layered　perovskite　can　significantly　influence　the　property　of　the　heterojunction　and　charge　transfer　process.　For　single　channel　devices　a　responsivity　of　5.87　x　10(2)　A　W-1　and　a　detectivity　of　5.13　x　10(12)　Jones　is　realized.