Passivation approach boosts stability of perovskite solar cells

Researchers from City University of Hong Kong (CityUHK) have developed a living passivator that enhances the stability and efficiency of perovskite solar cells. Led by Professor Feng Shien-ping, a professor in the Department of Systems Engineering at CityUHK, this innovative coating mimics sustained-release capsules in drugs, which continuously release chemicals to heal defects caused by environmental stressors like water and heat, making it a promising solution for next-generation perovskite photovoltaics.

Perovskite solar cells are known for their ability to convert sunlight into electricity, making them a viable contender for the next generation of solar panels. However, there are concerns about their long-term storage and operational stability. Various passivation strategies have been developed to improve their performance and reliability, but there is difficulty addressing new defects caused by exposure to water and heat over time during operation.

To overcome these challenges, the researchers developed new “living” passivators using a special material. The passivator leverages dynamic covalent bonds that activate upon exposure to moisture and heat, enabling it to evolve new passivators in response to environmental factors. This approach allows for real-time repair and maintenance of perovskite solar cells.

Experiments demonstrated that the passivator improves the performance and durability of perovskite solar cells. This new passivation strategy has achieved a photovoltaic conversion efficiency of over 25% and maintained operational stability for more than 1000 hours at high temperatures and in humid conditions. Dr Wang Weiting, the first author of the study, said applying a living passivator on the perovskite surface enhances its resistance to environmental factors like moisture and heat, thereby improving the stability of perovskite solar cells in hot and humid conditions and introducing a responsive approach to environmental stressors.

“Consider the resilience of plants and other living beings to various weather conditions, while perovskite solar cells deteriorate within months. The key difference lies in the ability of living organisms to regenerate and heal evolving defects. By incorporating a passivation mechanism that dynamically heals during operation, we can potentially unlock this regenerative concept for perovskite or other electronic devices,” Feng said.

The researchers are collaborating with industry partners to apply this technology to address issues related to ionic migration and instability in perovskite solar cells during the manufacturing and operation stages. Making them more stable could help make these solar cells more commercially viable. This technology could also be used in other applications, such as interfacial contact engineering in microelectronic devices.

The research findings have been published in the scientific journal Nature.

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