Effect of Molecular Packing on Field-Effect Performance of Single Crystals of Thienyl-Substituted Pyrenes

Abstract

A series of pyrene derivatives containing thienyl groups, 1−3, has been prepared using the Suzuki coupling reaction. Recrystallization from solution and physical vapor transport (PVT) method afforded different types of crystals of 1. From the mixture of isomers of 2, the 1,8-isomer preferably crystallized from solution, whereas the 1,6-isomer crystal was obtained by the PVT method. Fabricating single-crystal-based field-effect transistors of the above compounds we directly compared the field-effect performance between the devices of the two isoforms of 1 and those of the two isomers of 2. Though the overlap integrals were calculated to be only ∼10−3, the best hole mobility reached 0.02 cm2 V−1 s−1 for one of the single crystals of 1. Intriguingly, for both 1 and 2 only one type of the crystal shows the field-effect characteristics, indicating the significance of molecular packing even in the absence of band transport among the poorly coupled molecules. The estimated intermolecular overlap integrals for each compound also imply that the minimum overlap integral of ∼10−2 eV is required for detection of the field-effect characteristics.

Thienylphenothiazine integrated pyrenes: an account on the influence of substitution patterns on their optical and electroluminescence properties

“…This leads to a relatively low band gap for the tetra-substituted derivative PP4. When compared with the known thienylpyrenes, 24,38 the oxidation potentials of the new compounds are less positive attributable to the electron-richness arising from the phenothiazine end-capping. …”

“…Recently, Ashizawa et al explored a series of thienylpyrenes for OFET application and found them to exhibit excellent p-type performance. 24 Kimura et al investigated the utility of X-shaped poly-thienyl pyrenes in bulk heterojunction solar cells (BHJs) and found to exhibit decent device parameters. 25 Among the heterocyclic chromophores, phenothiazine is one of the prototypical molecules and its unique butterfly configuration and high electron rich character are beneficial for its potential function in optoelectronic applications.…”

1,8‐Substituted Pyrene Derivatives for High‐Performance Organic Field‐Effect Transistors

“…By introducing end-capped octyl groups and treatmento f the dielectric surface, thiophene-containing compound 1 exhibited higherm obility than 1,8-bis(2-thienyl)pyrene [18] and pyrene derivatives that were substituted at the 2,7- [15] and 1,3,6,8-positions. Based on DFT calculations, bithiophene-containing compound 2 was found to contain large amounts of steric hindrance.…”

“…[17] Pyrene-thiophene derivatives have been widely used in OFETs. [18] Ta king into account two favorable factors, that is, that terminal alkyl chains can act as ad riving force for molecular ordering in the solid state [19] and the length of conjugateds tructure, [20] we designed and synthesized two 1,8-substituted pyrene derivatives that were composed of ap yrene core, thiophene units, and end-cappedo ctyl chains. [18] Ta king into account two favorable factors, that is, that terminal alkyl chains can act as ad riving force for molecular ordering in the solid state [19] and the length of conjugateds tructure, [20] we designed and synthesized two 1,8-substituted pyrene derivatives that were composed of ap yrene core, thiophene units, and end-cappedo ctyl chains.…”

Organic Semiconductors for Field-Effect Transistors

“…Nonetheless, high mobilities of 1.2 cm 2 V −1 s −1 for holes and 3 cm 2 V −1 s −1 for electrons were obtained by judging from the transient photocurrent of the pyrene crystal and calculating from the overlap integrals between two molecules at room temperature [89]. Because of the nonplanar structure, the tetrasubstituted-derivatives using pyrene as core including 33 and 34 tend to afford low mobilities [90][91][92]. However, the derivatives 35 and 36 using pyrene as an end-capped group and linear pyrene derivative 37 showed high mobilities [93][94][95].…”