Solar cells generate power by converting photons from the sun into electricity through a mechanism called "the photovoltaic effect".  these so-called 1st Generation Solar cells have dropped in cost to approximately $3.50 per watt, or 35-50¢ per kilowatt-hour. This cost is still is too high as U.S. residential consumers pay on average about 8.5¢ per kilowatt-hour for their electricity.

For the PV industry to achieve a cost level that is competitive with traditional forms of electricity production, overall manufacturing and system costs must be reduced while power output improved, or held steady and lifetime maintained.

To achieve high power output, solar devices must take advantage of as much of the solar spectrum as possible as the photons absorbed by a solar cell directly impacts the power output.

The solar spectrum includes invisible ultraviolet (UV) light, the visible spectrum of colors -violet, indigo, blue, green, yellow, orange and red -- and the invisible infrared or IR spectrum.  Solar radiation includes wavelengths as short as 300 nanometers (nm) and as long as 4,045 nm or ~4 microns. The amount of incoming photons across the UV, visible and IR spectrums is about 3%, 45% and 52%, respectively.

Silicon devices efficiently absorb and convert solar energy up to about 1,050 nm, covering approximately 75% of the total photon flux from the sun.

It has long been understood that PCE performance could be improved by combining multiple materials with different absorption characteristics in a single device to create a broader spectral response than that of a device with a single material.

This combination of high power and ultra-low cost using an organic semiconductor system is called "4th generation" solar cells. Organic materials can be applied to virtually any surface using a method akin to spray painting. Production methods of this sort are easily adaptable to continuous, "roll-to-roll" or batch manufacturing processes and hold the promise of dramatically reduced production costs.

Despite these advantages, characteristics of the absorption and excitation process in organic semiconductors require active layers to be thinner than the thickness necessary for complete absorption of incident solar illumination.