Perovskite solar cells are a promising alternative to conventional silicon-based solar cells, offering higher potential power conversion efficiencies, lower-cost materials, and more sustainable manufacturing processes. Despite these advantages, challenges such as instability under light exposure, humidity, and mechanical stress have hindered their commercial viability. A critical factor contributing to this instability is the uneven distribution of cations in perovskite thin films, which leads to phase transitions that degrade the devices over time.
A research team led by Prof. ZHOU Yuanyuan, Associate Professor in the Department of Chemical and Biological Engineering and Associate Director of the Energy Institute at HKUST, has uncovered key nanoscale phenomena that impact PSC stability. They identified nanoscale groove traps at perovskite grain triple junctions as geometric sites that capture cations and slow their movement, preventing uniform distribution. To address this issue, the researchers employed a chemical additive approach using butylammonium acetate, which successfully reduced the depth of these groove traps by a factor of three. The improved PSCs achieved an efficiency close to 26% while demonstrating enhanced stability under standardized test conditions.
Prof. Zhou, the study's primary corresponding author, emphasized the novelty of their approach: "Most existing studies focus on microscopic or macroscopic levels to improve perovskite solar cells. Our team, however, investigated details down to the nanoscale in these PSCs. We used an advanced characterization technique called cathodoluminescence imaging to examine the relation between these nanoscale groove traps and cation distribution. This fundamental approach guided our engineering of these nanogrooves to homogenize the cation distribution and improve the cell performance."
Research Report:Nanoscopic cross-grain cation homogenization in perovskite solar cells
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Hong Kong University of Science and Technology
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