Important nanoscale phenomena announced for more efficient and stable perovskite solar cells

In significant advances in promoting the development of renewable energy generation, the Faculty of Engineering at Hong Kong University of Science and Technology (HKUST) is taking the lead by breaking through research into the nanoscale properties of perovskite solar cells (PSCs). The initiative has led to the development of more efficient and durable cells, significantly reducing costs and expanding applications, thus linking scientific research to the needs of the business community.

Compared to traditional silicon solar cells, PSCs can potentially achieve high power conversion efficiency, featuring low-cost materials and the use of more sustainable manufacturing processes. Therefore, PSC has become a cutting-edge research field in energy and sustainability.

However, the long-term stability of PSCs when exposed to light, humidity, and thermomechanical stressors remains a major hurdle for commercialization. One important factor causing instability is the heterogeneous distribution of cations in perovskite thin films. This can cause unfavorable phase transitions that gradually decompose the device.

A research team led by Professor Zhou Yuanyuan, an associate professor at Hkust’s Department of Chemistry and Bioengineering and associate director of the Institute of Energy, discovered that nanoscale groove traps at triple junctions of perovskite grains act as geometric traps that capture cations and slow down potential towards combined use.

The researchers used a rational chemical additive approach known as butylmonium acetate to reduce the depth of these nanoscale groove traps by three times. The resulting cation hemolytic PSCs showed an improvement in efficiency by nearly 26%. More importantly, these devices exhibit advantageous stability under a variety of standardized test protocols.

Professor Zhou, the main corresponding author of the study, said, “Most existing studies focus on microscopic or macroscopic levels to improve perovskite solar cells. However, our team investigated the details of these PSCs up to the nanoscale.

“To investigate the relationship between these nanoscale groove traps and cation distributions, we used an advanced characterization technique called casodoluminescence imaging. This basic approach promoted the engineering of these nanogloves, homogenized cation distribution and improved cellular performance.”

The findings were published in the journal Nature Nanotechnology in a paper entitled “Nanoscopic Crossgrain Cation Homogenization of Perovskite Solar Cells.”

Dr Hao Mingwei, a fellow Hkust Postdoctoral, the first author of this work, said, “Perovskite is a soft lattice material. Through our experiments, we have found notable structural features of perovskite thin films that are significantly different from traditional materials. With this potential game changer.”

Professor Mashid Ahmadi at the University of Tennessee, Knoxville, is the co-author of the work. Other collaborators are from Yale University, Oak Ridge National Institute, Uwaru University, and Hong Kong Baptist University.