Increased efficiency and stability of Dye-Sensitized Solar Cells (DSSC) photoanode by intercalation of Eosin Y into Zn/Al layered double hydroxide

Abstract

Layered Double Hydroxides (LDH) are versatile materials that can be applied to different fields. Recently their employment in Dye-Sensitized Solar Cells (DSSCs) technology has been reported. The heart of this technology is the photoanode, a semiconductor layer sensitized with dye molecules able to absorb the sunlight. However, the traditional dye molecules are quite expensive and sensitive to thermal degradation and the sensitization process requires time and costs. The possibility to directly intercalate the dye in the LDH interlayer makes these materials very promising as innovative photoanodes. This aspect in fact would help to reduce both the time and the costs, overcome charge-transfer and recombination phenomena issues and finally increase the Photo-Conversion Efficiency (PCE) and stability. In this work, an Eosin Y-intercalated ZnAl LDH was prepared by coprecipitation and applied as photoanode material. For this purpose, a screen-printing ink was formulated and then applied onto a conductive transparent substrate. Then, complete DSSC prototypes were assembled and tested. A comparison with an analogous LDH intercalated with terephthalate and sensitized with Eosin Y showed a beneficial effect due to the presence of the dye intercalated in the structure rather than adsorbed on the surface, increasing the stability (tested for 1500 h) and efficiency of the related DSSCs. A 0.11 mA cm−2 of JSC, 568 mV of VOC and a PCE of 0.019% were obtained for the Eosin Y intercalated LDH based photoanode. Moreover, the interaction between the intercalated dye and the LDH sheets allowed to reduce charge recombination phenomena and thus to increase VOC and PCE values.