Fused phthalimide-based A-DA?D-A small molecule: New protocol for n-type organic semiconductors

Development of well-conjugated building blocks by a concise and efficient synthetic procedure is crucial for organic electronics. In particular, for A-DA ' D-A-type (A = donor and D = acceptor) organic semiconductors, which are the most popular and successful small molecular acceptors, the limited number DA ' D fused cores limits the variety of these molecules. Herein, we report a new A-DA ' D-A-type small molecule, TIIC, containing an entirely new DA ' D fused core. The complete synthetic procedure, including a well-designed photocyclization step, resulted in above 50% total yield over five steps. TIIC shows strong light absorption in the complete visible region because of the extended pi-conjugation and strong intramolecular charge transfer. The deep lowest un-occupied molecular orbital energy level (-4.0 eV) of TIIC, which indicates the n-type semiconductor property, was further confirmed by the organic field-effect transistor performance with unipolar electron mobility of 3.51 x 10-4 cm2 V-1 s- 1.

Automated summary

The development of well-conjugated building blocks is crucial for organic electronics and particularly for A-DA ' D-A-type organic semiconductors. This study presents a new A-DA ' D-A-type small molecule, TIIC, with a completely new DA ' D fused core. A concise and efficient synthetic procedure resulted in over 50% total yield. TIIC exhibits strong light absorption due to extended pi-conjugation and strong intramolecular charge transfer. Its n-type semiconductor property was confirmed by the organic field-effect transistor performance with a unipolar electron mobility of 3.51 x 10^-4 cm^2 V^-1 s^-1.