Solution-Processable meso-Triarylamine Functionalized Porphyrins with a High Mobility and ON/OFF Ratio in Bottom-Gated Organic Field-Effect Transistors

A series of metal-free porphyrin molecules with functionalized triarylamines at the meso-position are designed and synthesized. All the functionalized porphyrins possess good thermal stability and high decomposition temperatures over 422 °C and also exhibited electrochemical reproducibility. The calculated ionization potentials are in the range of −5.01 to -5.42 eV, and electron affinity levels are in between −2.47 and −2.91 eV, which supports stable charge ejection. Organic field-effect transistor (OFET) devices with bottom-gate/top-contact architecture are fabricated by a solution-processable technique. OFETs with an active layer of porphyrin with electron-accepting trifluorophenyl groups gave the highest charge carrier mobility of 4.4 cm²/Vs and an on/off ratio of 10⁷. The obtained results indicate these compounds to be efficient hole-transporting materials. This research work presents the highest mobilities of the porphyrins reported until now.