Concerted effect of large molecular dyes and bulky cobalt complex redox couple to retard recombination in dye-sensitized solar cells

Abstract: Dye-sensitized solar cells (DSSCs) are prepared using a combination of various carbazole dye derivatives or a ruthenium (Ru) complex dye (N719) and cobalt (Co) complex or I−/I3 − redox couples. With the Co redox couple, the largest molecular dye (MK14) demonstrated a longer lifetime and higher V oc than that of N719 and a comparable lifetime and V oc to those of N719 and the I−/I3 − redox couple. These results are due to the enhanced blocking effect that is obtained with the large dye and redox couple combination, providing a longer distance between the TiO2 surface and Co complex oxidized species. Thus, employing bulky redox couples for organic dyes that possess higher dispersion forces is effective in increasing the electron lifetime. [Copyright &y& Elsevier]