There are, of course, a huge range of ongoing efforts to address this problem (this is not likely to be the last time we get an engineer answer to this question in this space). Among the most recent approaches to this problem comes from a team of physicists and engineers at MIT that is using computer modeling and advanced chip-manufacturing techniques.
In December of 2008, researchers from the Research Laboratory of Electronics, and the departments of Materials Science and Engineering and Physics applied an antireflection coating to the front of ultrathin silicon films, plus a novel combination of multi-layered reflective coatings and a tightly spaced array of lines to the backs of the films. The result is photovoltaic cells with as much as 50 percent more electrical output.
The carefully designed layers deposited on the back of the cell cause light to bounce around longer inside the silicon layer, giving it more time to deposit its energy and produce an electric current. Without these coatings, light would just be reflected back out into the surrounding air.
The work has attracted interest from industry for applications ranging from generating remote off-grid electricity to dedicated clean power. – Deborah Halber