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Abstract: Dye-sensitized solar cells (DSCs) were fabricated from mesoporous SnO2 electrodes, which were prepared from nano-sized SnO2 particles. Current–voltage characteristics of the DSCs were compared with DSCs prepared from conventional TiO2 electrodes, which have similar amount of adsorbed dye with the SnO2. As a result, short-circuit current of the SnO2DSC were comparable with that of the TiO2DSCs, and more than 15mA/cm2 was obtained with the SnO2 at the thickness of 10μm under one sun conditions. Electron diffusion coefficients and lifetimes in the SnO2 and TiO2 electrodes were measured, showing slower diffusion and longer lifetime in the SnO2DSC than in the TiO2. The results imply that the electron transport and transfer dynamics in such electrodes is dominated by the influence of intra-band charge traps, and the control of the trap conditions would be the key strategy to employ various metal oxides for such solar cells. [Copyright &y& Elsevier]

Abstract: The lifetime of electrons in the semiconductor electrode of dye-sensitized solar cells (DSSCs) is an important parameter determining the energy conversion efficiency. We propose a method to determine the electron lifetime by stepped current induced measurement of cell voltage in the dark (darkSCIM). Since this technique does not require the creation of photoinduced charges, the lifetime of devices with poorly injecting dyes, or indeed values for devices, which employ no sensitizer, can be determined. [Copyright &y& Elsevier]

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]