Oxadiazole-integrated heterocoronene discotics as ambipolar organic semiconductors

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2023-01, Vol.11 (3), p.98-985
• Main Authors: De, Ritobrata, De, Joydip, Gupta, Santosh Prasad, Bala, Indu, Ankita, Tarun, Pandey, Upendra Kumar, Pal, Santanu Kumar
• Format: Article
• Language: English
• Subjects: Charge transport; Liquid crystals; Optoelectronics; Organic semiconductors; Oxadiazoles; Room temperature; Self-assembly; Thin films; Transport phenomena; Transport properties
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d2tc04144h

The development of modern technologies has driven a quest for new semiconducting materials in optoelectronics, where self-assembled liquid crystal (LC) materials can play a potential role. The molecular engineering of disc-shaped LCs (DLCs) with suitable organic moieties, especially heterocyclic units, can lead to control over their columnar architecture in the nano-scale regime, which holds the key to tuning the charge-transport properties of the system. Here, we have successfully designed and synthesized room-temperature DLCs ( 1.1 , 1.2 and 1.3 ) with 1,3,4-oxadiazole functional units acting as electron-deficient linkers between a central heterocoronene core and the peripheral alkoxy phenyl units. All the derivatives exhibited a broad columnar hexagonal mesophase range with high isotropic temperatures. When employed in space-charge limited current (SCLC) devices, they showed ambipolar charge transport behaviour in thin films, with maximum hole and electron mobilities of the order of 10 −3 and 10 −5 cm 2 V −1 s −1 , respectively. Disc-shaped liquid crystals designed by introducing oxadiazole functional units into a heterocoronene system were explored in thin-film space-charge limited current (SCLC) devices. They were found to exhibit ambipolar semiconducting behavior.