All solid-state dye-sensitized solar cells (DSSCs), which have been pursued just in the past ten years, are reviewed here in terms of the historical background, the present situation and the developmental outlook. Recent efforts to fabricate high-efficiency solid-state DSSCs are summarized in this paper, as well as studies on the long-term operational stability of such solar cells. Studies on the extremely-thin-absorber solar cell (ETA-solar cell) are also reviewed. The operational mechanisms of solid-state DSSCs are compared to those of the liquid counterparts (dye-sensitized photoelectrochemical cells, DSPECs). Two main obstacles to high conversion efficiency of solar energy are highlighted herein for solid-state DSSCs, i.e., insufficient light absorption and large internal recombination loss. Possible resolutions for these obstacles are pointed out.


(Communicated by Kenichi HONDA, M.J.A.)