What if you could print solar panel using magic polymers?

New Polymer materials technology might lower the cost of electricity production using solar technology to below $1 per watt for the first time. This will finally enable mass-market, portable applications for photo-voltaic technology.

In the last technology report of Nature photonics, a new technology of materials for photovoltaic panel was introduced by Russell Gaudiana and Christoph Brabec.

Most of the photoactive materials used for photovoltaics in the past focused on silicon, which in fact dominates the commercial solar-energy field today. In recent years several other materials were tested as cheaper candidates for solar panel for instance amorphous silicon (a-Si), copper indiumgallium selenide (CIGS) and cadmium telluride (CdTe). All of these are now in different stages of commercialization. They all received the nick name: " thin-film technologies ", and they are considered cheaper in means of manufacturing and production throughput. These technology are expected to lower the consts of electricity production by solar devices to less than 1$ per watt.

However, a new technology has a better potential to dramatically lower the costs of solar energy production. This technology called "Bulk hetero-junction technology" is based on organic materials which are organic semiconductors, used as replacement to silicon. These new materials can be printed over sheets, with available roll-to-roll coating and printing techniques. This technology uses " abundantly available non-toxic materials, is based on a scalable production process with high productivity, and requires low investment from the manufacturer.

The idea is to use two different semiconductors called "p" and "n" with different conductance properties. Printing them together creates an electric device called diode. On light absorption, photo-induced charges are produced by ultra-fast charge transfer (few femto-seconds) between the two semiconductor types.

This technology encompasses carbon-based materials to use as "donor" and "acceptor" of electrons in the systems. The most popular class of organic donor molecules are conjugated polymers, like polythiophenes, polyfluorenes or polycarbazoles. The choice for acceptors is much narrower — for more than 10 years substituted fullerenes have given by far the best performance.

The advantage that separates this technology from all of the others is its compatibility with high-speed and low-temperature roll-to-roll processing. The procedures are similar to those used in the printing and coating industry in that solutions of the active materials, dissolved in organic solvents or water, are applied to a plastic sheet by means of a coating applicator.
Various printing and coating technologies have proven their compatibility with organic semiconductor processing, like flexo printing, gravure printing, screen printing, slot die coating and ink-jet printing.

Many advances in the past few years were done to improve the polymers efficiency and means of production. For more details, you should read this article at nature photonics VOL 2 MAY 2008 www.nature.com/naturephotonics