Dr. Tim Kelly and his team at the University of Saskatchewan (USask) have made key discoveries about why solar cells made with lead halide perovskite degrade prematurely. These discoveries could advance the reliability of a new generation of solar cells.
Graphic courtesy of Adobe.
In experiments conducted at the Canadian Light Source (CLS) synchrotron, Kelly, a professor of chemistry at USask, sought to determine why perovskite-based solar cells fail under certain conditions. Perovskite, a semiconductor material that requires significantly less energy to produce than traditional silicon, offers environmental advantages but has faced challenges with stability and durability.
The researchers initially suspected that the issue lay in the perovskite formulation. By employing X-ray diffraction to analyze the material’s atomic structure in real-time, the team observed that humidity played a critical role in cell degradation. Moisture caused ions within the perovskite to mobilize, migrate to the electrode, and corrode it, rendering the device inoperative.
“We thought humidity would degrade the perovskite because it tends to pick up moisture more readily,” explained Kelly. “But by observing the failure process at a microscopic scale, we could see that moisture increases ion mobility, leading to electrode corrosion.”
To address this issue, Kelly’s research team identified several potential solutions:
- Using corrosion-resistant materials for electrodes
- Adding buffer layers to block ion migration
- Fully encapsulating cells to prevent moisture exposure
“There’s a lot of promise to the material,” said Kelly, referring to perovskite. “Solving the moisture issue could lead to high-performing and reliable solar cells.”
The synchrotron experiments at CLS played a crucial role in these findings. The advanced instruments provided real-time data at unprecedented speeds, generating data points every one to two seconds compared to the 15-20 minutes required for similar tests in Kelly’s USask lab. “This allowed us to follow the process in real-time and observe how electrodes corrode,” Kelly noted.
Reflecting on the unexpected findings, Kelly remarked, “It’s always exciting for me as a scientist when you learn something new or something unexpected.”
This research has implications for developing weatherproof and reliable solar cells, a key step toward expanding their use in applications ranging from buildings and electric vehicles to wearable devices and toys.
D’Souza, Renita M., Onyebuchi I. Onumonu, Brayden N. Lehtonen, and Timothy L. Kelly. “Humidity Resistance of Inverted Perovskite Solar Cells as Measured by Operando X-ray Scattering.” ACS Applied Energy Materials (2024). https://doi.org/10.1021/acsaem.4c02470
