Ambipolar Columnar Self-assembled Organic Semiconductors based on Heteroatom bay-Annulated Perylene Bisimides

Highly electron-deficient heteroatom (N, S, Se) bay-annulated PBIs exhibiting ordered columnar phase over a wide mesomorphic range including ambient temperature are reported in this manuscript. These compounds with six peripheral n-decyloxy chains exhibited absorption spectra with high molar extinction coefficients, electron-deficient nature and self-assembling behaviour. A detailed comparison with the PBIs bearing six peripheral n-decyl chains was also carried out to get the valuable insights on the structure-property relations in this important class of organic semiconductors. Both of the PBI series were tested for their charge carrier mobility by space charge limited current method and found that they exhibit ambipolar conductivity. This is in contrary to the vast body of literature, where most of the PBI based semiconductors exhibit electron transport behaviour. In general, PBIs derived from tri-n-alkyl anilines exhibit higher mobility values than the PBIs derived from tri-n-alkoxy anilines. Especially, the ambipolar S-annulated PBI derived from tri-n-alkyl aniline exhibited highest hole (8.39×10^-3  cm² /V.s) and electron (1.5×10^-2  cm² /V.s) mobility values and promising for the application in organic electronics.