Synthesis of Terphenylene Compounds and Solution Processable Terphenylene Semiconductors for TFT

The linear terphenylene (benzo [3,4] cyclobuta [1,2-b I biphenylene) compounds were synthesized from tetrabromoterphenyls with lithiation followed by a four membered ring formation reaction using cupric chloride for the first time. Since the tetrabromoterphenyls were prepared by a palladium-catalyzed coupling reaction, this synthetic method can provide a wide range of symmetric and unsymmetric terphenylene compounds with high rigidity. It is known that the molecular structure of the unsubstituted terphenylene was almost planar and the arrangement of molecules was classified as a herringbone packing such as pentacene. TFTs were fabricated in 'top'-contact configuration on the HMDS-treated Si/SiO, substrate by vacuum deposition. Terphenylene compounds were purified by recrystallization, used as semiconductors, and we have found for the first time that they had p-channel field effect properties. Dibenzoterphenylene and naphthoterphenylene (TC1), which is an isomer of dibenzoterphenylene, exhibited mobilities of 0.0058 and 6.0 X 10(-4) cm2/V?s in air, respectively. Introducing substituents to TC1 developed soluble TC2 and TC3. The performance of devices using TC2 and TC3 were highly improved to give mobilities of 0.022 and 0.055 cm2/V ? s in air, respectively. Since a device of pentacene had a mobility of 0.033 cm2/V? s in air in the same conditions of fabrication, TC2 and TC3 have comparable performance to pentacene in air. TFT devices using TC2 and TC3 were also prepared by solution process and showed mobilities of 1.3 X 10 and 2.9 X 10 (3) cm2/V.s, respectively, without detailed investigation of coating conditions.