| abstract |
Photovoltaic cells disclosed comprising a structure according to formula I as shown below:wherein R1, R4, R8, R11, R15, R18, R22, and R25 are selected from the group consisting of hydrogen, fluorine, chlorine, methoxy, methyl, ethyl and cyano; wherein R31 and R29 are both hydrogen or together are a metal ion having a double positive charge or a metal ion plus non-metal atom or group bound to the metal ion, and having overall a double positive charge; and wherein R1, R4, R15, and R18 are the same and are a first substituent, and R8, R11, R22 and R25 are the same and are a second substituent which is different from said first substituent. |