High performance ambipolar organic semiconductors are highly desirable for organic logic circuits.Herein,we demonstrate the integration of sodium sulfonate(SS)-tethered sidechains into a diketopyrrolopyrrole-bbased ambipolar polymer(PDPP3T)can simultaneously improve its hole and electron transport performances either parallel or perpendicular to polymer film.Three SS-functionalized polymers(PDPP3T-xSS,x = 0.025,0.05 and 0.10)were synthesized and studied.It was found that SS functionalization can reinforce interchain π-π interactions,slightly lower frontier orbital energy levels,produce more rod-like structures in film,and change chain-packing from edge-on to face-on fashion,but has little influence on thermal properties.More interestingly,organic field-effect transistors reported hole mobility of 0.27±0.066 cm2·V-1·s-1 and electron mobility of 0.038±0.016 cm2·V-1·s-1 for PDPP3T,while increased 2.4 and 5 folds to 0.64 ± 0.087 and 0.19±0.051 cm2·V-1-s-1 for PDPP3T-0.025SS,respec-tively.Moreover,PDPP3T-XSS devices displayed reduced threshold voltages for both hole and electron transports.Meanwhile,space charge-limited cur-rent method found SS functionalization achieved an order of magnitude increase in electron mobility and slight enhancement in hole mobility transport-ing perpendicular to polymer film.In-depth investigations suggest such enhancements may originate from the joint actions of chain-stacking modulation and ionic doping effect.