A series of perylene diimide derivatives 2a～2d with the substitutions of secondary amino groups at bay positions, were synthesized via simple Ullmann reaction, and their energy levels were characterized. From the UV-vis absorption spectra, it was found that, after the introduction of secondary amino into the bay position, the band gaps of perylene diimides became narrower, and the maximum absorption peaks were significantly red-shifted while compared to non-substituted parent compound. Thus, their absorption bands extended to the near-IR range. Through cyclic voltammetry, it was disclosed that 2a, 2c, and 2d exhibited both reversible reduction and oxidation processes, and their HOMO energy levels increased greatly, indicating bipolar semiconductive characteristics. Preliminary investigation of the application of bis-morpholine substituted perylene diimide 2d in organic photovoltaic devices was performed, and the results demonstrated that 2d could be used as both electron acceptor and electron donor.

Key words: bay position, secondary amino group, perylene diimide, energy level, photovoltaic property