Nav: Home

New perovskite material shows early promise as an alternative to silicon

August 08, 2019

Silicon dominates solar energy products -- it is stable, cheap, and efficient at turning sunlight into electricity. Any new material taking on silicon must compete, and win, on those grounds. As a result of an international research collaboration, Shanghai Jiao Tong University, the Ecole Polytechnique Fédérale de Lausanne (EPFL), and the Okinawa Institute of Science and Technology Graduate University (OIST) have found a stable material that efficiently creates electricity -- which could challenge silicon hegemony.

Writing in Science, the collaborating teams show how the material CsPbI3 has been stabilized in a new configuration capable of reaching high conversion efficiencies. CsPbI3 is an inorganic perovskite, a group of materials gaining popularity in the solar world due to their high efficiency and low cost. This configuration is noteworthy as stabilizing these materials has historically been a challenge.

"We are pleased with results suggesting that CsPbI3 can compete with industry-leading materials," says Professor Yabing Qi, head of OIST's Energy Materials and Surface Sciences Unit, who led on the surface science aspect of the study.

"From this preliminary result we will now work on boosting the material's stability -- and commercial prospects."

Energy level alignment

CsPbI3 is often studied in its alpha phase, a well-known configuration of the crystal structure appropriately known as the dark phase because of its black color. This phase is particularly good at absorbing sunlight. Unfortunately, it is also unstable -- and the structure rapidly degrades into a yellowish form, less able to absorb sunlight.

This study instead explored the crystal in its beta phase, a less well-known arrangement of the structure that is more stable than its alpha phase. While this structure is more stable, it shows relatively low power conversion efficiency.

This low efficiency partly results from the cracks that often emerge in thin-film solar cells. These cracks induce the loss of electrons into adjacent layers in the solar cell -- electrons that can no longer flow as electricity. The team treated the material with a choline iodide solution to heal these cracks, and this solution also optimized the interface between layers in the solar cell, known as energy level alignment.

"Electrons naturally flow to materials with lower potential energy for electrons, so it is important that the adjacent layers' energy levels are similar to CsPbI3," says Dr. Luis K. Ono, a co-author from Professor Qi's lab. "This synergy between layers results in fewer electrons being lost -- and more electricity being generated."

The OIST team, supported by the OIST Technology Development and Innovation Center, used ultraviolet photoemission spectroscopy to investigate the energy level alignment between CsPbI3 and the adjacent layers. These data showed how electrons can then move freely through the different layers, generating electricity.

The results showed a low loss of electrons to adjacent layers following treatment with choline iodide --due to better energy level alignments between the layers. By repairing the cracks that naturally emerge, this treatment led to an increase in conversion efficiency from 15% to 18%.

While that leap may seem small, it brings CsPbI3 into the realm of certified efficiency, the competitive values offered by rival solar materials. Although this early result is promising, inorganic perovskite is still lagging. For CsPbI3 to truly compete with silicon, the team will next work on the trinity of factors allowing silicon's reign to continue -- stability, cost, and efficiency.
-end-


Okinawa Institute of Science and Technology (OIST) Graduate University

Related Science Articles:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.
Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.
Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.
Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.
Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.
More Science News and Science Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...