Solid-State NMR Exploration of Factors for Enhancement of Hole Mobility by Introduction of Poly(styrene) Into Poly(3-hexylthiophene)

Solid-state cross-polarization magic angle spinning (CPMAS) ¹³C NMR is employed to examine the morphological factors that contribute to the enhanced hole mobility observed in poly(3-hexylthiophene) (P3HT) by the introduction of electrically inert poly(styrene) (PSt). Chain mobilities of crystalline and amorphous phases in the P3HT domain are evaluated utilizing T₁^C (¹³C spin-lattice relaxation time in the laboratory frame). The crystallinity of P3HT component is estimated based on the spectral editing method through T_1ρ^H (¹H spin-lattice relaxation time in the rotating frame) filtered CPMAS. Moreover, the miscibility of P3HT crystalline and P3HT amorphous domains is estimated. These results suggest the formation of the rigid amorphous (short-range ordered amorphous) in a block copolymer (P3HT-block-PSt). An increase in the proportion of the crystallite and proximate presence of each crystallite in a blend sample of P3HT with PSt (P3HT-blend-PSt) are also indicated. Enhanced mobility is attributed to the larger portion of rigid amorphous domain for P3HT-block-PSt, and to higher crystalline content for P3HT-blend-PSt.