As　the　simplest　oligomeric　acceptors,　dimerized　acceptors　(DAs)　are　easier　to　synthesize,　and　more　importantly,　they　can　retain　good　intermolecular　interaction　and　photovoltaic　properties　of　their　parent　small-molecule　acceptors　(SMAs).　Nevertheless,　currently　most　efficient　DAs　are　derived　from　banana-shaped　acceptors　and　they　might　suffer　from　inferior　device　stability　with　high　diffusion　coefficients.　Herein,　we　design　and　synthesize　two　planar　DAs　(DMT-FH　and　DMT-HF)　by　bridging　two　linear-shaped　M-series　SMAs　with　a　thiophene　unit.　The　effects　of　fluorination　position　on　the　diffusion　coefficients,　power　conversion　efficiencies　(PCEs)　and　stability　of　the　DAs　are　systematically　studied.　Our　results　suggest　that　DMT-HF　with　fluorination　on　the　ending　indanone　groups　shows　enhanced　intermolecular　interactions,　improved　PCE　and　stability　compared　with　the　counterpart　(DMT-FH)　with　fluorination　on　the　central　indanone　groups.　Further　optimization　on　the　DMT-HF-based　devices　yields　an　outstanding　PCE　of　17.17　%,　which　is　the　highest　among　all　linear-shaped　SMA-based　DAs.　Notably,　with　the　low　diffusion　coefficient　(3.36x10-24　cm2　s-1)　of　DMT-HF,　the　resulting　device　retains　over　93　%　of　the　initial　PCE　after　5000　h　of　continuous　heating　at　85　degrees　C,　suggesting　its　excellent　thermal　stability.　The　results　highlight　the　importance　of　intermolecular　interaction　and　fluorination　for　achieving　efficient　and　stable　polymer　solar　cells.　An　ADA-type　small　molecule　acceptor　is　used　to　construct　a　dimerized　acceptor　(DMT-HF)　which　is　featured　with　a　high　glass　transition　temperature　and　a　low　diffusion　coefficient.　When　blended　with　a　wide　band　gap　copolymer,　the　resulting　DMT-HF-based　polymer　solar　cell　exhibits　an　excellent　efficiency　of　17.17　%　and　outstanding　thermal　stability.　image