In a groundbreaking development, materials engineers at Georgia Tech have tackled a significant hurdle in the realm of metal halide perovskite solar cells. Renowned for their impressive efficiency in converting light into electricity, these cells have long grappled with degradation issues when exposed to water and oxygen. The research team, led by Juan-Pablo Correa-Baena, unveiled a pivotal discovery: a thin layer of molecules, specifically phenethylammonium iodide (PEAI), proved capable of preventing degradation by effectively repelling water.
Metal halide perovskites stand out for their potential to revolutionize solar energy production and semiconductor manufacturing for various applications, including LEDs and phototransistors. Juan-Pablo Correa-Baena, the senior author of the study and an assistant professor in the School of Materials Science and Engineering at Georgia Tech, emphasized the transformative possibilities of perovskites, stating, “We can think about them for applications in quantum information technology, such as light emission for quantum communication. These materials have impressive properties that are very promising.”
The instability of metal halide perovskites in the presence of water and oxygen has been a persistent challenge. When exposed to these elements, the perovskites undergo a structural transformation that compromises their ability to generate solar power effectively. Employing advanced techniques such as X-ray scattering and spectroscopy, the Georgia Tech team delved into the chemical interactions between perovskites and their environment.
The researchers uncovered the intricate interplay between water, oxygen, and perovskites that leads to instability. By isolating one of these factors, they managed to preserve the perovskites' energy-capturing crystal structure. “Before this paper, people thought if you expose them to just water, these materials degrade. If you expose them to just oxygen, these materials degrade. We've decoupled one from the other,” explained Correa-Baena.
To put their discovery to the test, the team applied a thin coating of PEAI on a perovskite film. PEAI molecules, known for their water-repelling properties, successfully stabilized the perovskites' structure, resulting in improved power conversion efficiency. However, PEAI presented challenges related to thermal stability. As the perovskite cells absorbed sunlight and heated up, the movement of PEAI molecules led to a drop in efficiency.
Addressing this thermal stability issue has become the focus of the next phase of research. Correa-Baena is collaborating with Georgia Tech chemist and materials scientist Antonio Facchetti to develop new molecules that not only prevent water interactions but also remain stable at high temperatures. This ongoing effort represents the next chapter in Georgia Tech's commitment to advancing solar energy technology.
Correa-Baena envisions a future where Georgia plays a prominent role in solar manufacturing activities. “Industry is already very interested, with companies around the U.S. popping up and trying to commercialize this. All the technology that we're creating here at Georgia Tech is eventually going to be able to be translated into industry,” he stated. The aim is to foster an ecosystem where Georgia emerges as a leader in solar manufacturing, encompassing cutting-edge technologies like perovskites.
Source: Georgia Institute of Technology