Polymer　acceptors　based　on　the　polymerization　of　small-molecule　acceptor　(PSMAs)　have　developed　rapidly　in　recent　years.　All-polymer　solar　cells　(all-PSCs)　composed　of　PSMAs　and　polymer　donors　not　only　retain　the　excellent　mechanical　properties,　but　also　have　better　morphological　properties　than　traditional　polymer　acceptors　such　as　N2200.　However,　since　PSMAs　are　generally　not　highly　polymerized,　their　electron　mobilities　are　generally　lower　than　the　hole　mobilities　of　the　high-molecular-weight　polymer　donors　they　are　used　with.　In　this　work,　we　apply　the　sequential　processing　(SqP)　method　and　use　toluene　as　the　processing　solvent　to　prepare　PSMA-based　all-PSCs,　which　effectively　improves　the　electron　mobility　and　shows　much　higher　efficiency　(15.8　%)　than　the　SqP　device　prepared　from　chloroform　(13.9　%)　–　the　conventional　solvent　used　for　high-performance　PSMAs.　Not　only　that,　the　efficiency　of　the　toluene-processed　SqP　device　is　also　higher　than　that　of　the　device　prepared　by　the　traditional　blending-casting　(BC)　method　(14.2　%).　In　addition,　for　the　first　time,　we　reveal　the　film　formation　process　of　all-polymer　active　layers　prepared　by　the　SqP　method　using　the　in　situ　UV-Vis　absorption　technique,　and　investigate　the　vertical　phase　separation　and　the　rate　of　exciton　generation　across　the　device　using　film-depth-dependent　absorption　spectroscopy,　which　systematically　explained　the　effect　of　increased　mobility　on　device　parameters.　This　methodology　is　applied　in　two　different　all-polymer　systems,　namely,　PM6:PYF-T-o　and　PM6:PY-IT,　and　both　systems　manifest　the　same　conclusion.　©　2022