Northwestern University develop tin-based solar energy cell

5 May 2014 (Last Updated May 5th, 2014 18:30)

Researchers at the Northwestern University have developed a tin-based solar energy cell, which would replace lead in perovskite-based solar cells.

Researchers at Northwestern University have developed a tin-based solar energy cell, which would replace lead in perovskite-based solar cells.

The researchers have revealed that tin could be used as a low-cost and environmentally safe light-absorbing material in these cells.

Perovskite solar has achieved 15% efficiency, while the tin perovskite should be able to match, and possibly surpass, the same efficiency.

Northwestern University inorganic chemist Mercouri G. Kanatzidis said, "This is a breakthrough in taking the lead out of a very promising type of solar cell, called a perovskite.

"Tin is a very viable material, and we have shown the material does work as an efficient solar cell."

The new solar cell uses perovskite along with tin instead of lead as the light-absorbing material.

Kanatzidis, who led the research, has developed, synthesised and analysed the material.

The solid-state tin solar cell is essentially a sandwich of five layers.

The first layer is glass that allows sunlight to enter the cell and it is followed by a layer of titanium dioxide. Together they act as the electric front contact of the solar cell.

Next, the tin perovskite, the light absorbing layer, is deposited. This is done in a nitrogen glove box.

On top of that the transport layer is added to close the circuit and obtain a functioning cell.

"Perovskite solar has achieved 15% efficiency, while the tin perovskite should be able to match, and possibly surpass, the same efficiency."

Researchers have used a substituted pyridine molecule to create this structure.

The final layer is made of gold, while the entire device is about one to two microns thick.

The team has tested the device under simulated full sunlight and discovered that it recorded a power conversion efficiency of 5.73%.

McCormick School of Engineering and Applied Science professor of materials science and engineering and a co-author of the study Robert PH Chang said, "Our tin-based perovskite layer acts as an efficient sunlight absorber that is sandwiched between two electric charge transport layers for conducting electricity to the outside world."

Kanatzidis added, "Other scientists will see what we have done and improve on our methods.

"There is no reason this new material can't reach an 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."

Kanatzidis and Chang have said the new tin perovskite solar cell with promises of higher efficiency and lower fabrication costs while being environmentally safe.

The Argonne-Northwestern Solar Energy Research (ANSER) Center director of operations and outreach Dick Co said, "This union between solid-state inorganic chemistry and solar cell device fabrication is one of the many hallmarks of the collaborative culture at the ANSER Center.

"Solving the global energy problem will require a multidisciplinary approach, and this work illustrates the importance of team science in achieving breakthroughs."

Energy