Improved Self-Assembly of P3HT with Pyrene-Functionalized Methacrylates

Abstract

A block copolymer with discotic liquid crystalline behavior was synthesized using Grignard metathesis polymerization (GRIM) and initiators for continuous activator regeneration atom transfer radical polymerization (ICAR-ATRP). A novel discotic liquid crystalline mesogen, 6-(pyren-1-yloxy)hexyl methacrylate (PyMA), comprises a block that is attached to regioregular poly(3hexylthiophene) (rr-P3HT) generated by GRIM and subjected to end-group modification. Due to the continuous regeneration of Cu + in the reaction mixture in ICAR-ATRP compared to conventional methods, the synthesis was successfully performed with less catalyst. The purity and yield of the final product are increased by eliminating rigorous post-synthesis purification. Stacked pyrene units have contributed to the enhanced long-range π−π interactions and aligning of the P3HT block as observed in thin-film X-ray diffraction (XRD). Furthermore, field-effect mobilities in the order of 10 −2 cm 2 V −1 s −1 in bottom-gate, top-contact organic field-effect transistors (OFETs) suggest an enhancement in charge transport due to the discotic electron-rich pyrene units that help mitigate the insulating effect of the methacrylate backbone. The formation of uniform microdomains of P3HT-bpoly(PyMA) observed with tapping mode atomic force microscopy (TMAFM) on the channel regions of OFETs indicates the unique packing of the block copolymer in comparison to pristine P3HT. Thermotropic properties of the novel discotic mesogen in the presence and absence of P3HT were observed with both the poly(3-hexylthiophene)-b-poly(6-(pyren-1-yloxy)hexyl methacrylate) (P3HT-b-poly(PyMA)) block copolymer and poly(6-(pyren-1-yloxy)hexyl methacrylate) (poly(PyMA)) homopolymer using polarized optical microscopy (POM) and differential scanning calorimetry (DSC).

Synthesis of Anthracene and Pyrene End‐Capped Triarylamines for p‐Channel High‐Performance OFETs

“…Furthermore, the high HOMO level of the compounds reduces the energy barrier for charge injection from metal electrodes. This mobility is relatively large in OFETs compared with the previously reported pyrene‐based p ‐channel semiconductors [57,58] . The OFET device based on device 8 c reached the mobility of 1.2 cm 2 /Vs with an on/off current ratio of 10 5 and threshold voltage of −3 V. Compound 8 c has an almost similar backbone to 9 c , differs by only the end‐capping unit (pyrene replaced by anthracene), but display significant variation in structural, morphological and electrical characteristics.…”

“…This mobility is relatively large in OFETs compared with the previously reported pyrene-based p-channel semiconductors. [57,58] The OFET device based on device 8 c reached the mobility of 1.2 cm 2 /Vs with an on/off current ratio of 10 5 and threshold voltage of À 3 V. Compound 8 c has an almost similar backbone to 9 c, differs by only the end-capping unit (pyrene replaced by anthracene), but display significant variation in structural, morphological and electrical characteristics. SEM, XRD, and FMO orbital seek to explain the origin of the self-assembling nature in these compounds and characterize the electronic distribution in the molecular orbital in the context of the slight structural alteration they present.…”

Luminescent assemblies of pyrene-containing bent-core mesogens: liquid crystals, π-gels and nanotubes

“…On the other hand, liquid crystals [25][26][27] have provided a variety of classical layered or columnar anisotropic functional selfassemblies, also incorporating pyrene units, [28][29][30][31][32][33][34][35][36][37][38] providing a control over their organization that determines their optical and electronic properties. However, only a few suitable molecular design strategies providing both types of soft materials in the route to versatile functional materials have been published.…”

Photoelectric and Self-Assembly Properties of Tetrasubstituted Pyrene Discotic Derivatives

“…Pyrene molecules with a large conjugated structure, good fluorescence properties, and chemical stability are one of the ideal structures for self-assembled discotic liquid crystal molecules [ 13 , 14 , 15 ]. Organic molecules with pyrene as the core are widely used in the field of probes because of their high fluorescence efficiency and excimer formation [ 16 , 17 , 18 ]. Many pyrene derivatives also show liquid crystal (LC) behavior [ 19 ].…”