| abstract |
Disclosed is an electron donating organic material that can provide a photovoltaic element with a high photoelectric conversion efficiency. The electron donating organic material comprises a benzothiadiazole compound satisfying requirements that (a) a benzothiadiazole skeleton and an oligothiophene skeleton are contained, (b) the bandgap (Eg) is not more than 1.8 eV, and (c) the level of the highest occupied molecular orbital (HOMO) is not more than -4.8 eV. In the benzothiadiazole compound, the benzothiadiazole skeleton and the oligothiophene skeleton are alternately covalently bonded. The benzothiadiazole skeleton : oligothiophene skeleton ratio is in the range of 1 : 1 to 1 : 2 excluding 1 : 1. The number of thiophene rings contained in one oligothiophene skeleton is 3 or more and 12 or less. |