Science Inventory

MANUFACTURE OF PHOTOVOLTAIC SOLAR CELL USING PLANT CHLOROPHYLL

Impact/Purpose:

e one developed by Aoki et al.

As a possible extension beyond this project, the effect of the central coordinated atom could be investigated by substituting the Mg atom in chlorophyll with other metals such as calcium and scandium to determine if better properties may be obtained. The high cost of manufacturing silicon-based photovoltaics (cost/watt) has been an obstacle to widespread adoption. Nonetheless, the use of PV cells has been growing at a rate of 25–30% over the past several years. A simplified process for producing chlorophyll-based PV cells could result in an increased number of entrepreneurial startups, especially in remote areas which there is need for off-the-grid energy. Reducing costs and increasing volume output would lower the price of each cell, making it a reasonable alternative to silicon-based solar cells. The development of practical organic solar cells would lower the world-wide demand for fossil fuels and deliver humanitarian benefits. The proposed work will also contribute to the ongoing effort of St. Lawrence University to use P3 Concepts as an educational tool.

e one developed by Aoki et al.

As a possible extension beyond this project, the effect of the central coordinated atom could be investigated by substituting the Mg atom in chlorophyll with other metals such as calcium and scandium to determine if better properties may be obtained. The high cost of manufacturing silicon-based photovoltaics (cost/watt) has been an obstacle to widespread adoption. Nonetheless, the use of PV cells has been growing at a rate of 25–30% over the past several years. A simplified process for producing chlorophyll-based PV cells could result in an increased number of entrepreneurial startups, especially in remote areas which there is need for off-the-grid energy. Reducing costs and increasing volume output would lower the price of each cell, making it a reasonable alternative to silicon-based solar cells. The development of practical organic solar cells would lower the world-wide demand for fossil fuels and deliver humanitarian benefits. The proposed work will also contribute to the ongoing effort of St. Lawrence University to use P3 Concepts as an educational tool.

The need for renewable energy is a global concern, due to increasing energy consumption patterns worldwide and the inevitable depletion of the world’s oil reserves. Because of the demand for a cheap, efficient, clean, and renewable energy source, photovoltaic (PV) cells have emerged as a viable energy source, and a promising material for their manufacture is chlorophyll. Chlorophyll-based (organic) PV cells show great potential for developing widely available and practical non-fossil fuel-based energy. These organic solar cells operate on the same principle as the familiar silicon cells. However, instead of being manufactured at high temperatures (1900°C), organic PV cells are fabricated using less-expensive carbon-based compounds at room temperature. We propose to study the viability of producing chlorophyll-based solar cells as a supplement to ‘grid’ electricity.

Initially, we will build on the pioneering work of Aoki et al. at Otia University in Japan. Their study tested chlorophyll a with 4-imidazole-acetic acid (Im) as an axial ligand (MgChl-a-Im) absorbed on a nanocrystalline TiO2 film (MgChl-a-Im/TiO2) electrode as a photosensitizer in the visible region. Our project will extend their work, first by using extracted chlorophyll from spinach for preliminary trials. Once we have shown the reaction works as planned, we will expand the process and use purchased chlorophyll. Another cell will be prepared from a mixture of chlorophyll a and chlorophyll b. The absorbed wavelengths of light absorbed by the organic PV cells will be analyzed using spectroscop

Description:

To date, we have successfully manufactured working chlorophyll sensitized solar cells using chlorophyll (and b mixture) from spinach leaves. We have evaluated the electronic characteristics (voltage, current, and power outputs using different loading resistors) of this solar cell against a TiO2 control cell without a chlorophyll sensitizer under two different sets of light exposure (indoors with a white bulb; and outdoors with natural sunlight, and over the course of three weeks). The solar energy conversion efficiencies were obtained for different illuminating conditions. The results show that the chlorophyll sensitized TiO2 based solar cell yielded 20 times higher maximum power when exposed to outdoor natural sunlight, and 45 times higher maximum power when exposed to a 40W white bulb compared with the non-sensitized control TiO2 cell. This is a clear indication that the chlorophyll has indeed sensitized the solar cell by allowing the solar cell to absorb the visible light range, whereas the non-sensitized TiO2 cell absorbs mainly in UV range. The monitoring of the performance of the solar cell over the course of three weeks provided important data on its viability. Manufacture of more chlorophyll-TiO2 solar cells is underway to enable more systematic evaluation of these cells under the experimental conditions originally proposed. Manufacture of solar cells with chlorophyll a or b, as shown in Aoki et al. 2005, will be carried out this summer to allow for the comparison study originally proposed.

URLs/Downloads:

Final Progress Report

Record Details:

Record Type: PROJECT (ABSTRACT)
Start Date: 08/30/2007
Completion Date: 08/29/2008
Record ID: 187266

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL CENTER FOR ENVIRONMENTAL RESEARCH