High Electrical Conductivity and Hole Transport in an Insightfully Engineered Columnar Liquid Crystal for Solution‐Processable Nanoelectronics

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-06, Vol.20 (23), p.e2308983-n/a
• Main Authors: De, Ritobrata, Maity, Madhusudan, Joseph, Alvin, Gupta, Santosh Prasad, Nailwal, Yogendra, Namboothiry, Manoj A. G., Pal, Santanu Kumar
• Format: Article
• Language: English
• Subjects: Carrier mobility; Charge transport; Current carriers; discotic liquid crystals; Electric contacts; Electrical resistivity; Electronics; Hole mobility; hole‐transport; Liquid crystals; Nanoelectronics; Organic semiconductors; Self-assembly; Semiconductors; solvatochromism
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202308983

Discotic liquid crystals (DLCs) are widely acknowledged as a class of organic semiconductors that can harmonize charge carrier mobility and device processability through supramolecular self‐assembly. In spite of circumventing such a major challenge in fabricating low‐cost charge transport layers, DLC‐based hole transport layers (HTLs) have remained elusive in modern organo‐electronics. In this work, a minimalistic design strategy is envisioned to effectuate a cyanovinylene‐integrated pyrene‐based discotic liquid crystal (PY‐DLC) with a room‐temperature columnar hexagonal mesophase and narrow bandgap for efficient semiconducting behavior. Adequately combined photophysical, electrochemical, and theoretical studies investigate the structure‐property relations, logically correlating them with efficient hole transport. With a low reorganization energy of 0.2 eV, PY‐DLC exhibits superior charge extraction ability from the contact electrodes at low values of applied voltage, achieving an electrical conductivity of 3.22 × 10−4 S m−1, the highest reported value for any pristine DLC film in a vertical charge transport device. The columnar self‐assembly, in conjunction with solution‐processable self‐healed films, results in commendably elevated values of hole mobility (≈10−3 cm2 V‐1s−1). This study provides an unprecedented constructive outlook toward the development of DLC semiconductors as practical HTLs in organic electronics. This work investigates functional nanofilms of semiconducting discotic liquid crystals (DLCs), designed by the synthetic engineering of a cyanovinylene‐integrated pyrene core toward a room‐temperature columnar hexagonal mesophase. The defect‐free DLC‐film shows effective hole extraction, resulting in remarkably high values of electrical conductivity (10–4 S m−1) and hole mobility (10−3 cm2 V‐1s−1).