In　this　paper,　a　novel　vertical　phototransistor　was　reported　and　compared　with　planar　phototransistors　for　the　first　time.　As　compared　with　the　planar　phototransistors,　the　vertical　ones　exhibited　much　better　photoelectric　performance,　which　is　attributed　to　an　ultrashort　photo-generated　holes　transfer　distance　and　a　stronger　excitons　dissociating　electrical　field　due　to　their　ultrashort　channel　length　(tens　of　nanometers).　Moreover,　in　order　to　examine　the　transport　and　trapping　of　different　carrier　charges　separately,　the　impact　of　[6,6]-phenyl　C61-butyric　acid　methyl　ester　(PCBM)　dopant　on　the　performance　of　planar　and　vertical　phototransistors　was　investigated.　The　vertical　devices　exhibited　an　ultrahigh　responsivity　(6600　A/W)　as　well　as　an　excellent　detectivity　(∼　7　×　1015　Jones)　and　a　fast　photoresponse　(rise　time　of　0.28　s),　whereas　slight　changes　were　observed　in　the　planar　ones　with　doping　of　PCBM.　The　high　performance　of　the　blend　vertical　phototransistors　is　due　to　the　trapping　of　the　photo-generated　electrons　with　PCBM　and　the　effective　transport　of　holes　due　to　the　ultrashort　channel　length.　This　paper　provided　a　promising　pathway　for　low-cost,　high-performance　phototransistors.　©　2019　IEEE.