Solvent　vapor　annealing　has　been　widely　used　in　organic　photovoltaics　(OPV)　to　tune　the　morphology　of　bulk　heterojunction　active　layer　for　the　improvement　of　device　performance.　Unfortunately,　the　effect　of　solvent　removal　rate　(SRR)　after　solvent　annealing,　which　is　one　of　the　key　factors　that　impact　resultant　morphology,　on　the　morphology　and　device　performance　of　OPV　has　never　been　reported.　In　this　work,　the　nanoscale　morphology　of　small　molecule　(SM):fullerene　bulk　heterojunction　(BHJ)　solar　cell　from　different　SRRs　after　solvent　annealing　was　examined　by　small-angle　neutron　scattering　and　grazing　incidence　X-ray　scattering.　The　results　clearly　demonstrate　that　the　nanoscale　morphology　of　SM:fullerene　BHJ　especially　fullerene　phase　separation　and　concentration　of　fullerene　in　noncrystalline　SM　was　significantly　impacted　by　the　SRR.　The　enhanced　fullerene　phase　separation　was　found　with　a　decrease　of　SRR,　while　the　crystallinity　and　molecular　packing　of　SM　remained　unchanged.　Correlation　to　device　performance　shows　that　the　balance　between　pure　fullerene　phase　and　mixing　phase　of　SM　and　fullerene　is　crucial　for　the　optimization　of　morphology　and　enhancement　of　device　performance.　Moreover,　the　specific　interfacial　area　between　pure　fullerene　phase　and　mixing　phase　is　crucial　for　the　electron　transport　and　thus　device　performance.　More　importantly,　this　finding　would　provide　a　more　careful　and　precise　control　of　morphology　of　SM:fullerene　BHJ　and　offers　a　guideline　for　further　improvement　of　device　performance　with　solvent　annealing.　©　2017　American　Chemical　Society.