Solar cells combine nanotech with plastics

A new generation of solar cells that combines nanotechnology with plastic electronics has been launched with the development of a semiconductor-polymer photovoltaic device by researchers in the US Dept. of Energy's Lawrence Berkeley National Laboratory.

It is claimed that such hybrid solar cells will be cheaper and easier to make than their semiconductor counterparts and could be made in nearly the same infinite variety of shapes a pure polymers.

It has been demonstrated that semiconductor nanorods can be used to fabricate readily processed and energy-efficient hybrid solar cells together with polymers.

At the heart of all photovoltaic devices are two separate layers of material, one with an abundance of electrons that function as a "˜negative pole', and one with an abundance of electron holes (vacant, positively-charged energy spaces) that functions as a "˜positive pole'.

When photons from the sun or some other light source are absorbed, their energy is transferred to the extra electrons in the negative pole. This electrical current can then be used to power other devices.

In a typical semiconductor solar cell, the two poles are made from n-type and p-type semiconductors. In a plastic solar cell, they are made from hole-acceptor and electron-acceptor polymers. In the hybrid solar cell, a semicrystalline polymer known as poly (3-hexylthiophene) or P3HT, for the hole acceptor or negative pole, and nanometer-sized cadmium selenide (CdSe) rods as the positive pole.