Source: Tamara M. Powers, Department of Chemistry, Texas A&M University

Today's modern world requires the use of a large amount of energy. While we harness energy from fossil fuels such as coal and oil, these sources are nonrenewable and thus the supply is limited. To maintain our global lifestyle, we must extract energy from renewable sources. The most promising renewable source, in terms of abundance, is the sun, which provides us with more than enough solar energy to fully fuel our planet many times over.

So how do we extract energy from the sun? Nature was the first to figure it out: photosynthesis is the process whereby plants convert water and carbon dioxide to carbohydrates and oxygen. This process occurs in the leaves of plants, and relies on the chlorophyll pigments that color the leaves green. It is these colored molecules that absorb the energy from sunlight, and this absorbed energy which drives the chemical reactions.

In 1839, Edmond Becquerel, then a 19-year old French physicist experimenting in his father's lab, created the first photovoltaic cell. He illuminated an acidic solution of silver chloride that was connected to platinum electrodes which generated a voltage and current.¹ Many discoveries and advances were made in the late 19^th and first half the 20^th century, and it was only in 1954 that the first practical solar cell was built by Bell Laboratories. Starting in the 1950s, solar cells were used to power satellites in space.²

Solar cells are electrical devices that utilize light to create a current. This video demonstrates preparation and testing of one such type of cell, the dye-sensitized solar cell (DSSC). First invented at UC Berkeley by Brian O'Regan and Michael Grätzel, Grätzel pursued this work at the École Polytechnique Fédérale de Lausanne in Switzerland, culminating in the first highly efficient DSSC in 1991.³ These solar cells, like plants, use a dye to help harness energy from the sun.