Synthesis of Phenanthro[9,10-d]imidazoles and their Potential Applications in Solution Processable Bottom-Gated OFETs

Phenanthro[9,10-d]imidazole is synthesized by employing Radziszewski method and further functionalized through palladium catalyzed Suzuki cross-coupling reaction. Solution processable organic field-effect transistors (OFETs) are assembled in bottom gate-top contact architecture. A binary solvent system comprising of chloroform/toluene in the ratio of 1/1 is preferred for the deposition of active semiconducting layer. The fabricated devices demonstrated excellent p-type characteristics with a good mobility, high ON/OFF ratio of 10(9) and a minimum threshold voltage of -4.5 V. Computational investigations indicted proper charge separation of the energy levels for the phenanthro[9,10-d]imidazole containing nitro group. Frontier molecular orbitals and the packing patterns obtained from computational studies suggest an efficient band gap for better device operation. The ordered morphologies of the molecules obtained from SEM analysis prove to be beneficial in the OFET performance. The photophysical, electrochemical and thermal properties of the molecules are studied in detail. The research work majorly emphasized on structural designing of the phenanthro[9,10-d]imidazoles for potential applications in organic devices.