UCLA Breakthrough Could Lead to More Durable, Less Expensive Solar Cells

A global group led by UCLA researchers has developed a manner to make use of perovskite in photo voltaic cells whereas defending it from the situations that trigger it to deteriorate. Credit score: Yang Lab/UCLA

Utilizing enhanced halide perovskite rather than silicon might produce cheaper units that get up higher to gentle, warmth.

Amid the entire efforts to transform the nation’s power provide to renewable sources, solar energy nonetheless accounts for rather less than 3% of electrical energy generated within the U.S. Partially, that’s due to the comparatively excessive value to provide photo voltaic cells.

One approach to decrease the price of manufacturing can be to develop photo voltaic cells that use less-expensive supplies than at the moment’s silicon-based fashions. To attain that, some engineers have zeroed in on halide perovskite, a sort of human-made materials with repeating crystals formed like cubes.

In principle, perovskite-based photo voltaic cells may very well be made with uncooked supplies that value much less and are extra available than silicon; additionally they may very well be produced utilizing much less power and a less complicated manufacturing course of.

However to date, a stumbling block has been that perovskite breaks down with publicity to gentle and warmth — notably problematic for units meant to generate power from the solar.

Yepin Zhao, a UCLA postdoctoral researcher and first creator of the research, holds a perovskite-based photo voltaic cell. Credit score: Yang Lab/UCLA

Now, a global analysis collaboration led by UCLA has developed a way to use perovskite in solar cells while protecting it from the conditions that cause it to deteriorate. In a study that was published recently in Nature Materials, the scientists added small quantities of ions — electrically charged atoms — of a metal called neodymium directly to perovskite.

They found not only that the augmented perovskite was much more durable when exposed to light and heat, but also that it converted light to electricity more efficiently.

“Renewable energy is critically important,” said corresponding author Yang Yang, the Carol and Lawrence E. Tannas, Jr. Professor of Engineering at the UCLA Samueli School of Engineering and a member of the California NanoSystems Institute at UCLA. “Perovskite will be a game changer because it can be mass produced in a way silicon cannot, and we’ve identified an additive that will make the material better.”

Halide perovskite’s ability to convert light to electricity is due to the way its molecules form a repeating grid of cubes. That structure is held together by bonds between ions with opposite charges. But light and heat tend to cause negatively charged ions to pop out of the perovskite, which damages the crystal structure and diminishes the material’s energy-converting properties.

Diagrams showing the structure of an unaltered perovskite molecule (left) with iodine ions (purple) migrating away; and a perovskite molecule with neodymium ions (red) added to help retain iodine ions. Credit: Yang Lab/UCLA

Neodymium is commonly used in microphones, speakers, lasers and decorative glass. Its ions are just the right size to nestle within a cubic perovskite crystal, and they carry three positive charges, which the scientists hypothesized would help hold negatively charged ions in place.

The researchers added about eight neodymium ions for every 10,000 molecules of perovskite and then tested the material’s performance in solar cells. Working at maximum power and exposed to continuous light for more than 1,000 hours, a solar cell using the augmented perovskite retained about 93% of its efficiency in converting light to electricity. In contrast, a solar cell using standard perovskite lost half of its power conversion efficiency after 300 hours under the same conditions.

The team also shined continuous light on solar cells without any equipment drawing power, which accelerates the degradation of perovskite. A device using perovskite with neodymium retained 84% of its power conversion efficiency after more than 2,000 hours, while a device with standard perovskite retained none of its efficiency after that amount of time.

To test the material’s ability to withstand high temperatures, the researchers heated solar cells with both materials to about 180 degrees Fahrenheit. The solar cell with augmented perovskite held onto about 86% of its efficiency after more than 2,000 hours, while a standard perovskite device completely lost its ability to convert light to electricity during that time.

In many previous studies aimed at making perovskite more durable, researchers have experimented with adding protective layers to the material, but that has largely failed. The idea to augment the material itself came from lead author Yepin Zhao, a postdoctoral researcher in Yang’s lab. Zhao said he was inspired by a technique commonly used in the production of silicon semiconductors — adding small amounts of other compounds to modify the material’s properties.

“The ions tend to move through the perovskite like cars on the highway, and that causes the material to break down,” Zhao said. “With neodymium, we identified a roadblock to slow down the traffic and protect the material.”

Yang said the advance could help perovskite solar cells reach the market within the next two to three years.

Reference: “Suppressing ion migration in metal halide perovskite via interstitial doping with a trace amount of multivalent cations” by Yepin Zhao, Ilhan Yavuz, Minhuan Wang, Marc H. Weber, Mingjie Xu, Joo-Hong Lee, Shaun Tan, Tianyi Huang, Dong Meng, Rui Wang, Jingjing Xue, Sung-Joon Lee, Sang-Hoon Bae, Anni Zhang, Seung-Gu Choi, Yanfeng Yin, Jin Liu, Tae-Hee Han, Yantao Shi, Hongru Ma, Wenxin Yang, Qiyu Xing, Yifan Zhou, Pengju Shi, Sisi Wang, Elizabeth Zhang, Jiming Bian, Xiaoqing Pan, Nam-Gyu Park, Jin-Wook Lee and Yang Yang, 17 November 2022, Nature Materials.
DOI: 10.1038/s41563-022-01390-3

Other UCLA authors of the study are Shaun Tan, Tianyi Huang, Rui Wang and Jingjing Xue, who earned doctorates; postdoctoral researchers Dong Meng and Tae-Hee Han; doctoral students Wenxin Yang and Qiyu Xing; Anni Zhang, who recently earned a master’s degree; and undergraduates Yifan Zhou and Elizabeth Zhang. Other co-authors are from Marmara University in Turkey, Sungkyunkwan University in Korea, Dalian University of Technology and Westlake University in China, Washington State University, UC Irvine and Washington University in St. Louis.

The research was funded by the U.S. Department of Energy, Korea’s National Research Foundation, China’s National Natural Science Foundation and Turkey’s Scientific and Technological Research Council.