Perovskite solar cells (PSCs) with ultra-high stability and high efficiency have been achieved thanks to a molecular crosslinker developed by XlynX Materials, according to a new study, led by researchers at Fudan University and the University of Victoria. A key finding shows 99% stability after 1,000 hours of continuous illumination.
Over the past decade there has been continued research into performance improvements for PSCs because they are lower cost, lighter weight and easier to manufacture over silicon solar cells. However, there have been roadblocks to commercialization particularly around long-term stability and efficiency.
According to a recent IDTechEx report, resolving perovskite PV stability issues has been a challenge with many of the solutions resulting in tradeoffs or additional costs. But progress has been made to advance the stability of PSCs from academia to the industry. The report indicates that pilot studies and trials are currently in progress with several companies ready to enter the perovskite PV market in the next two to three years.
Sources of degradation (Source: IDTechEx)
The first reported perovskite solar cell in 2009 had an efficiency of only 3.9% and 10 years later there are reported efficiencies of over 25%, which is comparable to conventional silicon technology, according to IDTechEx. Despite the demonstration of high-efficiency perovskite modules, said the market research firm, there are still concerns over long-term stability that degrades the electronic and optical properties of the module.
IDTechEx said there are two methods to improve stability. One is “to encapsulate the cell to prevent the ingress of environmental elements,” and the other method “involves tuning the perovskite’s chemical composition to improve the resistance of the material.” But there are tradeoffs that impact other properties of the solar cell. “Encapsulation techniques and material engineering are crucial to preventing the degradation of the perovskite film.”
Thin-film solar panel installation (Source: XlynX Materials)
A new solution to the stability challenge
XlynX Materials explained that when the volatile organic components, also called organic cations, in the perovskites are exposed to environmental stimuli like light, heat and electric fields, they can migrate or escape from the perovskite layer, which leads to rapid degradation, significantly reducing efficiency, stability and performance of PSCs.
Over the years, researchers have been looking for ways to protect the perovskite material from environmental exposure to increase stability and efficiency. XlynX Materials believes the solution has been found with its BondLynx molecular crosslinker, or bonding agent, which is “used to covalently bond with the organic cations in the PSCs.”
How the crosslinker works (Source: XlynX Materials)
The study, published in the research journal, Joule, reported several performance improvements, including nearly 99% stability after 1,000 hours of continuous illumination using the BondLynx treatment. This is comparison to untreated PSCs that showed a 35% loss in power conversion efficiency after 200 hours of continuous operation under 1 sun illumination (1 kW/m2), according to researchers.
The PSCs also achieved high thermal stability using BondLynx, maintaining nearly 98% efficiency after 600 hours of continuous operation when exposed to constant heat (60°C). The untreated PSCs exhibited poor thermal stability, losing 27% efficiency under the same conditions.
Researchers also demonstrated high efficiency. The treated PSCs achieved a high efficiency of over 24% with operational stability over 1,000 hours.
“The reason BondLynx is effective is because it forms chemical covalent bonds with the organic components in PSCs to strongly immobilize them, thereby reducing the losses of efficiency, stability, and performance typically seen in PSCs,” according to XlynX. “With no significant reduction in performance over the course of the study, the stability improvements realized by BondLynx are expected to extend far beyond the 1,000-hour mark.”
The researchers also indicate that the ultra-stable PSCs have potential in other perovskite-based optoelectronic devices. These could include perovskite LEDs, photodetectors and sensors.
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