Dithieno[3,2-c:3′,2′-h][2,6]naphthyridine-4,9(5H,10H)-dione-based Quinoidal Small Molecules: Synthesis, Properties, and Optoelectronic Applications

Amide and imide groups have been widely used in the design of organic semiconductors, and the development of new structure semiconductors based on these functional groups is of great interest to further improve the performance of organic electronic devices. Herein, we designed and synthesized two novel 5,10-dihydrodithieno[3,2- c :3′,2′- h ][2,6]naphthyridine-4,9-dione (TVTDA) based quinoidal molecules with different side chains, TVTDA-CN-EH and TVTDA-CN-OD. Both molecules showed the deep lowest unoccupied molecular orbital (LUMO) and the deep highest occupied molecular orbital (HOMO) energy levels and strong absorption in the long wavelength region. Organic field-effect transistors (OFETs) based on TVTDA-CN-EH and TVTDA-CN-OD exhibited unipolar n-type electron transport behavior with mobilities of 0.04 and 0.0064 cm 2 ·V −1 ·s −1 , respectively. TVTDA-CN-EH with shorter alkyl side chains demonstrated better electron transport properties, which is attributed to the larger grain size in the film to facilitate charge transport. Furthermore, organic phototransistors (OPTs) based on TVTDA-CN-EH film showed good photo detection property from red light to near infrared region. Our work provides a new idea for the design and synthesis of organic semiconductors, especially for n-type organic semiconductors with photoresponse in the long wavelength.