Highly Segregated Lamello‐Columnar Mesophase Organizations and Fast Charge Carrier Mobility in New Discotic Donor–Acceptor Triads

Abstract

Four new donor-acceptor triads (D-A-D) based on discotic and arylene mesogens have been synthesized by using Sonogashira coupling and cyclization reactions. This family of triads consists of two side-on pending triphenylene mesogens, acting as the electron-donating groups (D), laterally connected through short lipophilic spacers to a central perylenediimide (PI), benzo[ghi]perylenediimide (BI), or coronenediimide (CI) molecular unit, respectively, playing the role of the electron acceptor (A). All D-A-D triads self-organize to form a lamello-columnar oblique mesophase, with a highly segregated donor-acceptor (D-A) heterojunction organization, consequent to efficient molecular self-sorting. The structure consists in the regular alternation of two disrupted rows of triphenylene columns and a continuous row of diimine species. High-resolution STM images demonstrate that PI-TP2 forms stable 2D self-assembly nanostructures with some various degrees of regularity, whereas the other triads do not self-organize into ordered architectures. The electron-transport mobility of CI-TP2, measured by time-of-flight at 200 °C in the mesophase, is one order of magnitude higher than the hole mobility. By means of this specific molecular designing idea, we realized and demonstrated for the first time the so-called p-n heterojunction at the molecular level in which the electron-rich triphenylene columns act as the hole transient pathways, and the coronenediimide stacks form the electron-transport channels.

Nonlinear Nonacenes with a Dithienothiophene Substructure: Multifunctional Compounds that Act as Columnar Mesogens, Luminophores, π Gelators, and p‐Type Semiconductors

“…[10,12,[19][20][21] Liquid-crystalline (LC) semiconductors with π-conjugated polycyclic aromatic hydrocarbon (PAH) rigid cores, surrounded by soft side chains have attracted considerable research interests due to their exceptional one-dimensional self-organizational behavior, defect-self-healing character, and chargecarrier transport ability. [22][23][24][25][26] The design of novel π-conjugated polycyclic cores is therefore the key to improve the performances of liquid-crystalline (LC) semiconductors. In the last decade, LCs based on fused-thiophene subunits have been flourishing, and organic mesogenic derivatives of oligothiophenes, [27][28][29][30][31][32] thienothiophenes (TT), [33,34] dithienothiophenes (DTT), [35][36][37][38][39][40] benzothiophenes (BT), [41][42][43][44] benzotrithiophenes (BTT), [45,46] benzothieno [3,2-b]benzothiophene (BTBT), [47][48][49][50][51][52] materials have been amply reported.…”

Self‐Sorting in Supramolecular Assembly of π‐Systems

“…Donnio and co‐workers designed a few donor‐acceptor‐donor type molecular triads (11) for segregated mesophase organizations . The electron donating triphenylene mesogen and accepting perylenediimide (PDI) is connected through a short lipophilic spacer (Figure ).…”

Mesogenic complementary absorbing dyads based on porphyrin and perylene units

“…Since the so-called p-n heterojunction exists at the molecular level, these D-A DLCs possess fast intramolecular photoinduced electron transfer and form charge separated states [29][30][31][32][33]. Some D-A DLCs yield dual pathways along molecular columns to transfer electrons and holes [34,35]. At present, the discogens used in these D-A DLCs are limited in triphenylene, anthraquinone, perylene and BODIPY derivatives [36][37][38][39][40][41][42].…”