In 1891, R Appleyard wrote that one day the Sun, by means of photo-voltaic (electric) cells may lead to the total extinction of steam engines, and the utter repression of smoke coming out of the boiler chimneys. This may be a little far off, but the day when you can cover the roof of your house with panels of dye-sensitized solar cells or organic solar ceils to light your home and run your gadgets is approaching. Experts all over the world have developed a range of colored dyes for use in dye sensitized solar cells, that will enable us generate electricity from sunlight at a 1/1Oth of the cost of current silicon-based photo electric solar cells.
The synthetic dyes are made from simple organic compounds closely related to those found in nature. The green dye is synthetic chlorophyll derived from the light-harvesting pigment, which plants use for photosynthesis. Other dyes being tested in the cells are based on hemoglobin, the compound that gives blood its color. The newly made green solar cells are more environmentally friendly than silicon-based cells as they are made from titanium dioxide- a plentiful, non-toxic white mineral obtained from beach sands; the ore for Titanium oxide is available in abundance along the beaches of Kerala and Tamil Nadu in India.
Whereas currently used silicon cells need direct sunlight to operate efficiently, these news cells will work efficiently in low diffused light conditions when the sky is cloudy.
The expected cost is 1/1Oth of the price of a silicon-based solar panel, making them more attractive and accessible to home-owners. The dye sensitized solar ceils could be manufactured in a process which is similar to printing and they could be applied to windows. The cells would serve as tinted panes, letting half the light through and using the other half to generate electricity.
The photovoltaic (PV) effect is the basic physical process through which a PV cell converts sunlight into electricity. Firstly, solar energy concept was given shape by Fritts but his solar cells were very inefficient converters of energy; they transformed less than 1 per cent of the absorbed light energy into electrical energy. Though inefficient by today's standards, these early solar cells fos¬tered among some a vision of abundant, clean power.
Later, with time and technology, concentrator solar cell, a type of device in which sunlight is concentrated onto the cell surface by means of lenses, achieved an efficiency of 37 per cent due to the increased intensity of the collected energy. In general, solar cells of widely varying efficiencies are now available.
Energy that reaches earth from sunlight in one hour is more than that used by all human activities in one year. The new organic solar cells could also be made in different colors, making them an attractive architectural material. It is high time that we think of alternate resources of energy so that we give coming generations a cleaner environment to breathe.