New Multilayer Solar Cell Achieves High Efficiencies and Low Costs
Every day more energy falls on the Earth from the Sun than humanity uses, but harnessing that energy is difficult. Systems do exist to capture that energy, but many are plagued with high costs and/or low efficiencies. Researchers at the University of Illinois though have developed a multilayer solar cell that can tap into a large portion of the spectrum cheaply enough to compete with more traditional power sources.
Typical solar cells are limited to only capturing light of a certain, small range of frequencies, which puts a limit on the potential energy output they can achieve. By combining materials into the same cell, more energy can be captured and put to use. Also these designs have a higher theoretical limit on efficiency. The cells built by the Illinois researchers are quadruple-junction and have a triple-junction cell for a top layer and diffused-junction germanium cell for the bottom layer. While the top layer will absorb light with wavelengths from 300 nm to 1300 nm, the bottom layer can draw from wavelengths between 1300 nm and 1700 nm.
When individually tested the efficiency of the solar cells reached 43.9%, but under more practical conditions it only got to 36.5%. That still puts these cells at a significantly higher efficiency than other photoelectric technologies, and as these can be produced using a printing method, the energy generation costs of these cells could drop to below that of many other power sources.
Source: University of Illinois