Tailoring Phase Transition in Poly(3-hexylselenophene) Thin Films and Correlating Their Crystalline Polymorphs with Charge Transport Properties for Organic Field-Effect Transistors

Abstract

Poly(3-hexylselenophene) (P3HS) carries attractive advantages over their close analogue poly(3-hexylthiophene) (P3HT), including a stronger intermolecular interaction, a better interchain charge hopping, and a narrower bandgap. However, P3HS is much less studied compared to P3HT. Herein, we report on intriguing reversible phase transition between two different crystalline polymorphs (i.e., form I and II) in P3HS thin films with different molecular weights enabled by alternating thermal and solvent vapor annealing. More importantly, the phase transition kinetics and mechanism as well as the associated changes on molecular packing structures were also scrutinized. The correlation between different P3HS crystalline polymorphs and the resulting field-effect mobilities was explored for the f irst time. Our study provides an insight into P3HS crystallization and phase transition, thus entailing the use of polyselenophene-based materials for a wide range of optoelectronic applications.

Ring‐Banded Spherulitic Crystals of Poly(3‐butylthiophene) via Controlled Solvent Evaporation

“…Semiconducting conjugated polymers have demonstrated great promise for emerging applications in flexible electronic devices via cost‐effective, solution‐based processing methods such as roll‐to‐roll printing . Controlling the structure and morphology of the conjugated polymer in solution or under solvent annealing is critical for device performance . In general, conjugated polymers form 1D nanowire‐like crystalline lamellae in poor solvents, which is mainly driven by strong π−π interactions between the conjugated backbones .…”

The study of aggregation dynamics of conjugated polymer solutions in UV-vis absorbance spectra by considering the changing rate of average photon energy

“…Since the aggregation process of conjugated polymer solutions is really complex with a large number of variations, it is necessary for us to study these aggregation processes systematically in-depth by studying the aggregation dynamics. Most of the papers that include the aggregation dynamics are using the amount of aggregated and soluble conjugated polymer [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. It can be easily known that the amount of aggregate or soluble conjugated polymer can provide us different information in a curve at a time in a UV-vis absorbance spectrum.…”

Synthesis of side-chain regioregular and main-chain alternating poly(bichalcogenophene)s and an ABC-type periodic poly(terchalcogenophene)

“…Structurally similar to thiophene, two other ve-membered heterocycles in the chalcogenophene family-selenophene and tellurophene, featuring group-16 Se and Te elements, respectively-have attracted considerable interest because (1) Se and Te atoms are larger and have d-orbitals of higher polarizability (relative to S) to induce strong Se/Se and Te/Te attractions, potentially strengthening their interpolymer interactions, [37][38][39][40][41] and (2) as the chalcogen becomes heavier, the p-electrons in selenophene and tellurophene tend to adopt a more quinoidal character with higher coplanarity, giving rise to narrower band gaps and bathochromic shis in their absorption. [42][43][44][45][46][47][48][49][50] The homopolymers 3alkylselenophene (P3AS) 51,52 and 3-alkyltellurophene (P3ATe) 53,54 have also been prepared using the KCTP. We were interested in studying the effects of incorporating two different chalcogenophenes into a single polymer to generate a new class of poly(bichalcogenophene)s. By integrating thiophene, selenophene, and tellurophene units in a single polymer in a controlled sequence, the properties of the polymer could presumably be tailored specically.…”

“…the diffraction patterns were essentially unchanged, but with enhanced signal intensities and slightly lower values of d p and d l . Interestingly, PSeTe exhibited two lamellar interlayer spacings (16.33 and 12.95 A), indicating the formation of two crystal phases with different types of side-chain interdigitation 52,71. …”