The exciton—an electron-hole pair—eventually splits into separate mobile charges, one positive and one negative, which diffuse to their respective electrodes and generate a flow of electric current that can be used as a power source. In reality, though, a single photon hitting a solar device can generate multiple excitons, and some of these decay and are “wasted” as heat. If scientists could understand the molecular details that underlie multiexciton formation, they might be able to design new types of solar cells that get more photovoltaic bang for their buck—that is, convert all of those excitons into electric current rather than losing some to heat. Achieving this feat could mean two or three times as much electric current for every photon absorbed.
by Mitch Jacoby |
March 02, 2015