Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Taking the lead out of a promising solar cell

05.05.2014

Environmentally friendly solar cell pushes forward the 'next big thing in photovoltaics'

Northwestern University researchers are the first to develop a new solar cell with good efficiency that uses tin instead of lead perovskite as the harvester of light. The low-cost, environmentally friendly solar cell can be made easily using "bench" chemistry -- no fancy equipment or hazardous materials.

"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."

Kanatzidis, who led the research, is the Charles E. and Emma H. Morrison Professor of Chemistry in the Weinberg College of Arts and Sciences.

The new solar cell uses a structure called a perovskite but with tin instead of lead as the light-absorbing material. Lead perovskite has achieved 15 percent efficiency, and tin perovskite should be able to match -- and possibly surpass -- that. Perovskite solar cells are being touted as the "next big thing in photovoltaics" and have reenergized the field.

Kanatzidis developed, synthesized and analyzed the material. He then turned to Northwestern collaborator and nanoscientist Robert P. H. Chang to help him engineer a solar cell that worked well.

"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," said Chang, a professor of materials science and engineering at the McCormick School of Engineering and Applied Science.

Details of the lead-free solar cell will be published May 4 by the journal Nature Photonics. Kanatzidis and Chang are the two senior authors of the paper.

Their solid-state tin solar cell has an efficiency of just below 6 percent, which is a very good starting point, Kanatzidis said. Two things make the material special: it can absorb most of the visible light spectrum, and the perovskite salt can be dissolved, and it will reform upon solvent removal without heating.

"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 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."

Perovskite solar cells have only been around -- and only in the lab -- since 2008. In 2012, Kanatzidis and Chang reported the new tin perovskite solar cell with promises of higher efficiency and lower fabrication costs while being environmentally safe.

"Solar energy is free and is the only energy that is sustainable forever," Kanatzidis said. "If we know how to harvest this energy in an efficient way we can raise our standard of living and help preserve the environment."

The solid-state tin solar cell is a sandwich of five layers, with each layer contributing something important. Being inorganic chemists, Kanatzidis and his postdoctoral fellows Feng Hao and Constantinos Stoumpos knew how to handle troublesome tin, specifically methylammonium tin iodide, which oxidizes when in contact with air.

The first layer is electrically conducting glass, which allows sunlight to enter the cell. Titanium dioxide is the next layer, deposited onto the glass. Together the two 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 -- the bench chemistry is done in this protected environment to avoid oxidation.

On top of that is the hole transport layer, which is essential to close the electrical circuit and obtain a functional cell. This required Kanatzidis and his colleagues to find the right chemicals so as not to destroy the tin underneath. They determined what the best chemicals were -- a substituted pyridine molecule -- by understanding the reactivity of the perovskite structure. This layer also is deposited in the glove box. The solar cell is then sealed and can be taken out into the air.

A thin layer of gold caps off the solar-cell sandwich. This layer is the back contact electrode of the solar cell. The entire device, with all five layers, is about one to two microns thick.

The researchers then tested the device under simulated full sunlight and recorded a power conversion efficiency of 5.73 percent.

###

The paper is titled "Lead-free solid-state organic–inorganic halide perovskite solar cells." In addition to Kanatzidis and Chang, other authors of the paper are Hao, Stoumpos and Duyen Hanh Cao, all of Northwestern.

Megan Fellman | Eurek Alert!
Further information:
http://www.northwestern.edu

Further reports about: Tin electricity glass inorganic materials solid-state structure sunlight

More articles from Power and Electrical Engineering:

nachricht A big nano boost for solar cells
18.01.2017 | Kyoto University and Osaka Gas effort doubles current efficiencies

nachricht Multiregional brain on a chip
16.01.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>