Solution-Processable Diketopyrrolopyrrole Derivatives as Organic Semiconductors for Organic Thin-Film Transistors

Solution-processable diketopyrrolopyrrole derivatives having acetylene, 2,5-bis(2-ethylhexyl)-3-(5-(phenylethynyl)thiophen-2-yl)-6-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (3), 2,5-bis (2-ethylhexyl)-3-(thiophen-2-yl)-6-(5-(thiophen-2-ylethynyl)thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c] pyrrole-1,4-dione (4), and 6,6′-((thiophene-2,5-diylbis(ethyne-2,1-diyl))bis(thiophene-5,2-diyl)) bis(2,5-bis(2-ethylhexyl)-3-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (5) were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). For the fabrication of thin films based on solution processable compounds, drop-casting (DC) and solution-shearing (SS) were employed. Thin films of compound 5 exhibited p-channel characteristics with carrier mobility as high as 5.7 × 10⁻⁴ cm²/Vs and a current on/off ratio of 10⁴–10⁶ for top-contact/bottom-gate OTFT devices.