Dye sensitized solar cells were developed in the early 90’s and have since gained significant interest in the scientific community. This has been mainly attributed to their low productivity cost and environmental friendliness. Such cells can be sensitized by ruthenium complex dyes adsorbed on titanium dioxide. The problem with this type of sensitization is that the metals used to sensitize the dyes generate a few disadvantages such as being environmentally non-friendly, tedious to fabricate and are expensive. Plant dyes act as sensitizers, which absorbs sunlight and convert solar energy into electric energy. Natural plant-based dye sensitized solar cells have thus gained significance due to their availability, non-toxicity, low cost, and environmental friendliness. This has thus triggered the search for natural pigments from non-toxic plants which are abundant in nature, can last in dry conditions and require simple and cheap extraction methods.
In a recent paper published in Chemical Physics Letters researchers led by professor Deepak Ganta from the School of Engineering, Texas A&M International University proposed a relatively simple and inexpensive method that can be used to develop dye sensitized solar cells from two types of natural plant-based dyes, extracted from a leaf of Aloe Vera and Cladode. They aimed at developing dye-sensitized solar cells using Aloe Vera and Cladode of Cactus extracts as natural sensitizers.
First, natural plant based dyes extracted from stems and leaves of Aloe Vera and Cladode of the thorn-less prickly pear cactus were obtained. Titanium dioxide nano-powder was used for the fabrication of the dye sensitized solar cells sensitized by natural plant dye extracts. The research team then investigated the optical properties of the dye using Fourier Transform spectroscopy and UV-Vis Absorption Spectroscopy. Eventually, the photochemical parameters of the dye sensitized solar cells were obtained from the current density-voltage curve, upon exposure to standard AM 1.5G sunlight source.
The authors of this paper observed that the dye extracts obtained from the cladode and Aloe Vera contained chlorophyll and anthocyanin adhesion promoters that were verified using the Fourier Transform spectroscopy and UV-Vis Absorption Spectroscopy measurements. The adhesion promoters were observed to help in efficient adsorption of plant dyes into the titanium dioxide film leading to photoelectric conversion. They then noted that the dye sensitized solar cells sensitized by cladode offered the highest conversion efficiency of 0.740%.
The higher conversion efficiency of the cladode sensitized dye sensitized solar cells can be attributed to the stronger adhesion promoters in its chlorophyll dye which provides a better charge transfer. Therefore, the use of natural plant-based dyes as sensitizers of dye sensitized solar cells is promising due to their low production cost, environmentally friendliness and have a simple and energy efficient assembly method.
D. Ganta, J. Jara, R. Villanueva. Dye-sensitized solar cells using Aloe Vera and Cladode of Cactus extracts as natural sensitizers. Chemical Physics Letters volume 679 (2017) pages 97–101.
School of Engineering, Texas A&M International University, Laredo, TX 78041, USA.Go To Chemical Physics Letters