Recent progress on tandem structured dye-sensitized solar cells

Tandem structured dye-sensitized solar cells (DSSCs) can take full advantage of sunlight, effectively broadening the absorption spectrum of the cell, resulting in a higher open circuit voltage or short circuit current than that of the conventional DSSC with single light absorber. The theoretical maximum efficiency is therefore suggested to be over the Schottky-Queisser limit of 33%. Accordingly, tandem design of DSSC is thought to be a promising way to break the performance bottleneck of DSSC. Besides, the tandem designs also broaden the application diversity of DSSC technology, which will accelerate its scale-up industrial application. In this paper, we have reviewed the recent progress on photo-electrochemical applications associated with kinds of tandem designs of DSSCs, in general, which are divided into three kinds: ntype DSSC + n-type DSSC, n-type DSSC + p-type DSSC and n-type DSSC + other solar conversion devices. The working principles, advantages and challenges of these tandem structured DSSCs have been discussed. Some possible solutions for further studies have been also pointed out together.