A new class of organic semiconductors for solution processed OTFTs: Synthesis and characterization of pyrrolo–perylene derivatives with different end groups

Abstract

New pyrrolo–perylene derivatives, a new class of organic semiconductor, were designed for solution processed organic thin film transistors (OTFTs). Newly designed 2-(naphthalen-2-yl)thiophene end capped pyrrolo–perylene, 3,10-bis(5-(naphthalen-2-yl)thiophen-2-yl)-1-(2-octyldodecyl)-1H-phenanthro[1,10,9,8-cdefg]carbazole (NTPP), and bithiophene end capped pyrrolo–perylene, 3,10-bis([2,2′-bithiophen]-5-yl)-1-(2-octyldodecyl)-1H-phenanthro[1,10,9,8-cdefg]carbazole (BTPP), were synthesized by Suzuki coupling and Stille coupling reaction, respectively. NTPP and BTPP showed good solubility in common organic solvents and were characterized by various spectroscopy. Solution processed OTFTs using BTPP exhibited high field-effect mobilities up to 0.11 cm2 V−1 s−1 with an on/off ratio of 1 × 104 and a very small threshold voltage of 0 V, while OTFTs using NTPP exhibited far lower performances. The high mobility of BTPP is attributed to three dimensional multi-layered crystalline structure based on the results of the two dimensional grazing incidence X-ray diffraction pattern analysis and theoretical calculation using Gaussian, together with morphological study.