While conventional organic solar cells are comprised of single sheets of material, the new “tandem” organic solar cell is made of two multilayered parts that work together to gather a wider range of the spectrum: they collect both the shorter and longer light wavelengths. The architecture of the cells — two organic photovoltaic cells with different light absorption characteristics linked by a transparent layer of titanium oxide — is the equivalent of two cells in series, said Heeger.
As a result, the tandem cell has a 6.5 percent efficiency.
“This is the highest level achieved for solar cells made from organic materials,” Heeger said.
Silicon-based solar cells typically convert about 12 percent to 15 percent of solar energy to electricity, while previous organic photovoltaic cells converted up to about 6 percent.
To provide energy for today’s electronics, organic photo cells need an efficiency of around 10 percent, but it shouldn’t take long to get there.
clipped from: www.goletavalleyvoice.com