Contrasting the Charge Carrier Mobility of Isotactic, Syndiotactic, and Atactic Poly((-carbazolylethylthio)propyl methacrylate).

Isotactic nonconjugated pendant electroactive polymers (NCPEPs) have recently shown potential to achieve comparable charge carrier mobilities with conjugated polymers. Here we report the broader influence of tacticity in NCPEPs, using poly((-carbazolylethylthio)propyl methacrylate) (PCzETPMA) as a model polymer. We utilized the thiol-ene reaction as an efficient postpolymerization functionalization method to achieve pendant polymers with high isotacticity and syndiotacticity. We found that a stereoregular isotactic polymer showed ∼100 times increased hole mobility (μ) as compared to both atactic and low molecular weight syndiotactic PCzETPMA, achieving μ of 2.19 × 10 cm V s after annealing at 120 °C. High molecular weight syndiotactic PCzETPMA gave ∼10 times higher μ than its atactic counterpart, comparable to isotactic PCzETPMA after annealing at 150 °C. Importantly, high molecular weight syndiotactic PCzETPMA showed a dramatic increase in μ to 1.82 × 10 cm V s when measured after annealing at 210 °C, which surpassed the well-known conjugated polymer poly(3-hexylthiophene) (P3HT) (μ = 4.51 × 10 cm V s). MD simulations indicated short-range π-π stacked ordering in the case of stereoregular isotactic and syndiotactic polymers. This work is the first report of charge carrier mobilities in syndiotactic NCPEPs and demonstrates that the tacticity, annealing conditions, and molecular weight of NCPEPs can strongly affect μ.