Electrochemical and optical studies of 1,4-diaminoanthraquinone for solar cell applications

Organic microelectronic devices performances are strongly dependant on the energy level alignment of their different constituents (electrode/organic, organic/organic). The cyclic voltammograms (CV) of 1.4-diaminoanthraquinone (1,4-DAAQ) have been measured. The CV curves of 1,4-DAAQ show a one electron reversible reduction and oxidation wave. The energy levels corresponding to the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the 1,4-DAAQ have been determined from the first oxidation and reduction potential respectively. The electrochemical energy gap deduced from these measures (E-g= LUMO-HOMO = 1.76 eV) agrees well with the optical energy gap (E-g similar to 1.8 eV). 1,4-DAAQ thin film has been used as electron acceptor in ITO/PEDOT:PSS/ZnPc/acceptor/LiF/Al solar cells. Perylene 3,4,9,10-tetracarboxylicdianhydre (PTCDA) has also been used as electron acceptor. The open circuit voltage value varies with the acceptor, which is in good agreement with their different HOMO values.