Purple Bacteria and Photovoltaics

Monday, May 10 2010

Purple bacteria are single celled microscopic organisms that were among the first life forms on Earth. The tiny organisms live in aquatic environments and use sunlight as their source of energy. Neil Johnson, a physicist at the University of Miami, thinks its cellular arrangement could be adapted for use in solar panels.

“Purple bacteria were recently found to adopt different cell designs depending on light intensity,” says Johnson. “Our study develops a mathematical model to describe the designs it adopts and why, which could help direct design of future photoelectric devices.”

Johnson collaborated with researchers from the Universidad de los Andes in Colombia.

Solar energy arrives at the cell in “drops” of light called photons, which are captured by the light-gathering mechanism of bacteria present within a special structure called the photosynthetic membrane. Inside this membrane, light energy is converted into chemical energy to power all the functions of the cell. The photosynthetic apparatus has two light harvesting complexes. The first captures the photons and funnels them to the second, called the reaction center (RC), where the solar energy is converted to chemical energy. When the light reaches the RCs, they close for the time it takes the energy to be converted.