The clear understanding of structure–property relationship of stretchable polymer semiconductors is essential. Herein, we investigate the effect of fluorination position on crystalline structure, charge carrier mobility, and stretchability of polymer semiconductors based on benzodithiophene–co–benzotriazole (BDT–co–BTA) configuration. All polymer thin films showed similar hole mobilities (μ ≈ 0.1 cm2/V–s); however, polymer thin films with non-fluorinated backbones exhibited improved thin film stretchability with the higher crack onset strain (εc ≈ 20 ~ 50%) than those of fluorinated counterparts (εc ≤ 10%). The enhanced stretchability of thin films with non-fluorinated backbone is presumably due to higher face-on ratio and π–π stacking distance than those of the other thin films. Our results provide design guidelines for high-performance and stretchable polymer semiconductors.