Electroluminescent Aggregation-Induced Emission-Active Discotic Liquid Crystals Based on Alkoxy Cyanostilbene-Functionalized Benzenetricarboxamide with Ambipolar Charge Transport
Indu Bala, Harpreet Kaur, Madhusudan Maity, Rohit Ashok Kumar Yadav, Joydip De, Santosh Prasad Gupta, Jwo‐Huei Jou, Upendra Kumar Pandey, Santanu Kumar Pal
Abstract
There is significant demand for molecular functional materials with tailored light-emissive and charge transport properties for their utilization in organic optoelectronic devices. Motivated by such promising properties, we present the synthetic design and emissive and semiconducting properties of aggregation-induced emission (AIE)-active columnar discotic liquid crystals based on cyanostilbene-modified benzenetricarboxamide derivatives (1a, 1b, and 1c). Enantiotropic mesomorphic behavior over a wide temperature range, including room temperature, with columnar hexagonal self-assembly was observed for all of the compounds. The space-charge limited current (SCLC) technique revealed the ambipolar charge transport for reported materials with balanced electron and hole transport of the order of 10–3 cm2/(V s). On the other hand, all of the compounds 1a–c were tested as emitter materials in solution-processed organic light-emitting devices at different concentrations with several hosts, viz., poly(vinylcarbazole) (PVK), 1,3-bis(N-carbazolyl)benzene (mCP), bis[3,5-di(9H-carbazol-9-yl)phenyl]diphenylsilane (SimCP2), and (carbazolyl)-1,10-biphenyl (CBP). The maximum luminance of 1255 cd/m2 corresponding to sky-blue emission was observed for compound 1a at 3.0 wt % with the CBP host.