Molecular engineering of small molecules donor materials based on phenoxazine core unit for solution-processed organic solar cells

A D-pi-A type small molecule POZ4 and a A-pi-D-pi-A type small molecule POZ6, in which phenoxazine was used as the central building block and dicyanovinyl was employed as the electron-withdrawing end-group, have been designed and synthesized. Compared with D-pi-A type donor material POZ4, the donor material POZ6 with A-pi-D-pi-A configuration shows much wider response to solar light. An efficiency of 5.60% was obtained for the POZ6: PC71BM based solar cells, and the device fabricated with POZ6:PC71BM (1 : 1) showed a much better balanced hole and electron mobility of 2.24 x 10(-4) cm(2) V-1 s(-1) and 3.17 x 10(-4) cm(2) V-1 s(-1), respectively.