As　a　prominent　printing　technique,　inkjet　printing　is　an　ideal　technique　for　the　mass　production　of　solution-processed　thin-film　transistor.　Therefore,　in　this　work,　the　inkjet-printed　organic　field　effect　transistor　(OFET)　was　investigated　on　different　dielectric　substrates,　especially　on　polymer-based　dielectrics,　which　have　great　potential　for　flexible　OFET　devices.　Comparing　with　metal　oxide　dielectrics,　polymer　dielectric　offered　a　higher　surface　roughness　and　worse　surface　wettability,　resulting　in　reduced　charge　mobility.　Meanwhile,　due　to　the　nature　of　polymer,　it　had　much　higher　leakage　current　than　metal　oxide.　Fortunately,　with　atomic　layer　deposition　of　a　thin　layer　of　Al2O3,　the　surface　properties　of　dielectric　layer　and　molecular　packing　of　semiconducting　layer　were　significantly　improved,　which　boosted　charge　mobility　from　0.08　to　0.65 cm2 V−1 s−1　along　with　significantly　reduced　leakage　current.　This　method　can　be　broadly　applicable　to　the　inkjet-printed　OFET　devices　and　flexible　OFET　devices　for　further　improvement　of　device　performance.　©　2018,　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.