Innovation Pipeline

Solar cells till now have been two-dimensional. But researchers are on the verge of altering that perspective with 3D solar cells. And you can bet your bucks it’ll be as big a shift as other moves to 3D–like electronic games and software interfaces.

What’s the advantage? Simple. 3D cells collect more incoming light and that could translate to a boost in overall efficiency, because the sun doesn’t have to be directly overhead to capture its photons.

Jud Ready, a senior research engineer at Georgia Tech Research Institute, says the team’s goal is to harvest more sunlight with cells shaped like blades of grass. These cells could also mean lighter systems with less space requirements than traditional photovoltaic systems.

The 100-micron-tall cells are built out of millions of vertically aligned carbon nanotubes. Researchers grow the carbon nanotube “towers,” then coat them with cadium telluride and cadmium sulfide, which serve as the p-type and n-type photovoltaic layers. Because the 3D design permits better absorption, the coatings can be made thinner. That boosts efficiency.

There are now supply shortages in the solar market. That has fueled investment. According to a report by research firm New Energy Finance in London, VCs and private equity firms put more than $2.2 billion into clean-energy companies in the first quarter of 2007. That’s a 58 percent increase over the same period the previous year. Solar and biofuels technologies attracted the most capital, garnering $514 million and $205 million, respectively.

The 3D design was described in the March 2007 issue of the journal JOM, published by the Minerals, Metals and Materials Society. The Air Force Office of Scientific Research, the Air Force Research Laboratory, NewCyte and Intellectual Property Partners sponsored the research.

There will be challenges scaling the manufacture of these cells. But one has to believe that receiving photons in 3D is just as enlightening as seeing in 3D. By Lee Bruno