Driven　by　the　success　of　quinoidal　units　for　enabling　high-performance　polymer　semiconductors,　herein　a　new　quinoidal　building　block　that　terminated　by　indandione　is　reported.　By　introducing　Br　atoms　into　the　terminal　benzene　rings　of　indandione,　two　CPs,　P2TbTI-DPP　and　P2TbTI-TIID,　are　synthesized　through　Stille　polycondensation.　The　strong　electron-withdrawing　ability　of　indandione-terminated　quinoidal　unit　enables　P2TbTI-DPP　and　P2TbTI-TIID　with　low-lying　LUMO　energy　levels　of　≈–3.90 eV.　Organic　thin-film　transistors　based　on　P2TbTI-DPP　and　P2TbTI-TIID　exhibit　n-type　transport　behavior.　Besides,　it　is　found　that　the　electron　mobility　of　these　two　polymers　is　weakly　dependent　on　the　annealing　temperature　due　to　the　near-amorphous　of　polymer　thin-film.　©　2023　Wiley-VCH　GmbH.