New Solar Cell to Use Tin Instead of Lead as Light Absorbing Material

Researchers have developed an economical and environmental friendly solar cell that uses tin instead of hazardous lead as light-absorbing material.

Researchers at Northwestern University have developed a new solar cell, which uses tin as the harvester of light and not lead.  This new solar cell uses a structure dubbed perovskite in which lead is replaced with tin for absorbing light. This new study offers solar cells with higher efficiency and lower fabrication cost.  

Perovskite solar cells have been touted as the 'next big thing in photovoltaics'. Solar cells that use lead perovskite offer 15 percent efficiency, researchers hope that the use of tin should produce the same efficiency and possibly surpass that of lead.  

"This is a breakthrough in taking the lead out of a very promising type of solar cell, called a perovskite," said Mercouri G. Kanatzidis, an inorganic chemist with expertise in dealing with tin. "Tin is a very viable material, and we have shown the material does work as an efficient solar cell."

The material was developed, synthesized and analyzed by Kanatzidis. The solar cell was engineered with the help of nonscientist Robert P. H. Chang.

According to Chang, the tin-based pervoskite plays an efficient role of a sunlight absorber that is clubbed between two electric charge transport layers for conducting electricity. The solid state tin solar cell has an effectiveness of less than 6 percent that is a good starting point.

Two factors that work in favor of the material are - its capability to absorb most of the visible light spectrum and  perovskite salt can be dissolved and on the removal of the solvent it can easily be reformed.

"Other scientists will see what we have done and improve on our methods," Kanatzidis said. "There is no reason this new material can't reach efficiency better than 15 percent, which is what the lead perovskite solar cell offers. Tin and lead are in the same group in the periodic table, so we expect similar results."

Solar energy is a free and sustainable energy.  By using it in an efficient way it is possible to enhance the standard of living and also preserve the environment.

The solid state tin solar cells are a mix of five layers. The first layer, an electrically conducting glass, permits sunlight to enter the cell. Titanium dioxide is the next layer that is deposited on the glass and the two act as electric front contact of solar cell. The light absorbing box is deposited through nitrogen glove box.

The device was tested under stimulated sunlight and a power conversion efficiency of 5.73 percent was recorded.