Two　novel　isomeric　polymers　P(DPPT-TT)　and　P(DPPTT-T)　based　on　thiophene-flanked　diketopyrrolopyrrole,　thieno[3,2-b]thiophene　and　thiophene　building　units　were　designed　and　synthesized　via　a　new　skeletal　isomerization　strategy.　This　study　emphasizes　on　the　impact　of　this　skeletal　isomerization　on　the　photoelectric　properties　and　organic　field-effect　transistor　(OFET)　performances　of　the　resulting　isomeric　polymers.　Both　polymers　show　similar　light　absorption　properties　and　excellent　thermostability　and　have　a　comparable　molecular　weight.　They　also　display　typical　p-type　characteristics　in　air-tested　OFETs.　However,　P(DPPTT-T)　exhibits　significantly　better　OFET　performances.　In　particular,　its　average　hole　mobility　reaches　2.14　cm2　V-1　s-1,　triple　that　of　P(DPPT-TT).　The　higher　mobility　of　P(DPPTT-T)　might　be　attributed　to　the　interconnected,　smooth　and　thicker　nanofibrillar　network　morphology　and　the　relatively　higher　crystallinity　of　its　thin　films,　and　its　conjugated　chains　possess　a　smaller　π-π　stacking　distance.　©　2019　The　Royal　Society　of　Chemistry.