Characterization of Natural Dye Extracted from Wormwood and Purple Cabbage for Dye-Sensitized Solar Cells

Ho Chang,Chih-Hao Chen,Tien-Li Chen,Xuan-Rong Lai,Mu-Jung Kao,Kun-Ching Cho

doi:10.1155/2013/159502

Abstract

This study used natural dyes as sensitizers of dye-sensitized solar cells (DSSCs) to replace expensive chemical synthetic dyes. We prepared two natural dyes, chlorophyll dye and anthocyanin dye, by extracting them from wormwood and purple cabbage, respectively. Moreover, we mixed the prepared chlorophyll dye and anthocyanin dye at 5 different volume ratios to form cocktail dyes. For preparation of photoelectrode, P25 TiO2nanoparticles were used to prepare paste, which was coated on fluorine-doped tin oxide (FTO) conductive glass by the spin coating method at different spin coating speeds in order to form TiO2thin films with different thicknesses. The DSSC prepared by the cocktail dye achieves photoelectric conversion efficiency (η) of 1.95%, open-circuit voltage (VOC) of 0.765 V, and short-circuit current density (JSC) of 5.83 mA/cm2. Moreover, the prepared DSSC sensitized solely by chlorophyll extract of wormwood achieved a photoelectric conversion efficiency (η) of 0.9%, whereas the DSSC sensitized solely by anthocyanin extract of purple cabbage achieved a photoelectric conversion efficiency of 1.47%, achieving the longest lifetime of electrons amongst these three dyes.

Highlights

In 1954, Bell Laboratories introduced a crystalline silicon solar cell with efficiency reaching 4.5%, bringing about the development of solar cells in the subsequent decades [1]
On the other hand, compared to the crystalline silicon solar cell, dye-sensitized solar cells (DSSCs) use a solid-liquid interface, which is produced from a solid-state semiconductor and an electrolyte as the driving force
After using the spin coating method to coat the paste on fluorine-doped tin oxide (FTO) conductive glass, thermal treatment was carried out, and a layer of thin film was obtained

Summary

Introduction

In 1954, Bell Laboratories introduced a crystalline silicon solar cell with efficiency reaching 4.5%, bringing about the development of solar cells in the subsequent decades [1]. Since ruthenium dyes are very rare and expensive, there is considerable interest in recent times toward the use International Journal of Photoenergy of natural organic dyes extracted from various plants, fruits, flowers, and leaves as molecular sensitizers in DSSCs [5]. Most of the natural dyes have narrower light absorption wavelength ranges, so that the photoelectric conversion efficiency of the prepared DSSC cannot be increased. Cocktail pigments make use of the light absorption complementary features of different pigments to increase the photoelectric conversion efficiency of DSSCs. Kumara extracted shisonin and chlorophyll from shiso leaves and mixed them to form cocktail dye. This study compared the effects of the DSSCs prepared by different natural dyes on voltage decay, lifetime of electrons, and incident photon to current efficiency (IPCE)

Experimental Details

Results and Discussion

Conclusions