Ecole Polytechnique Fédérale de Lausanne researchers have found a way to significantly improve the operational stability of perovskite solar cells at high temperatures, which is necessary for their use in terawatt power grids.
Perovskite solar cells (PSCs) have gained attention for their high power-conversion efficiencies and low-cost solution processing. However, ensuring their stability at high temperatures has been a challenge, as the points of contact between their different layers (“interfaces”) are susceptible to degradation, leading to energy loss and decreased performance.
In a new study published in Science, researchers have found that they can minimize PSC degradation at high temperatures by using fluorinated aniliniums, a class of compounds used in pharmaceuticals, agrochemicals, and materials science. The study was led by Michael Grätzel at EPFL, Edward Sargent at the University of Toronto, and Kenneth Graham at the University of Kentucky.
The researchers incorporated fluorinated aniliniums in the “interfacial passivation” step of PSC fabrication. Interfacial passivation is a technique used to enhance the stability and performance of interfaces between different layers or materials to minimize defects, reduce charge recombination, and improve overall efficiency and stability.
Adding fluorinated aniliniums enhanced the stability of PSCs by avoiding progressive ligand intercalation. This prevented the continuous penetration of ligand molecules between the layers or structures of the perovskite material, which destroys the integrity of the crystals, leading to degradation and decreased performance of PSCs.
Using this approach, the scientists achieved a certified quasi-steady-state power-conversion efficiency of 24.09% for inverted-structure PSCs. When they tested an encapsulated PSC – a device within a protective enclosure – at a temperature of 85°C, 50% relative humidity, and 1-sun illumination (the intensity of sunlight under normal, clear-sky conditions at solar noon), the device worked at its maximum power generation for an impressive 1560 hours (~65 days) while maintaining its functionality and efficiency.
The study is a major contribution to PSC stability and offers a potential solution for enhancing their performance, durability, and reliability in high-temperature environments, bringing us closer to the terawatt-scale deployment of this promising photovoltaic technology.
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This might very well get a niche production run of some substance as 85° C is 185° F. That’s a quite warm temperature, one that is close to lots of devices needed cooling systems to keep operating. An example is the thermostat in a gasoline engine will likely open for water cooling at about 185° F.
Absent the expertise to say, 185° might not be adequate for an equatorial solar cell installation. But in the upper temperate zone that just might be the line that makes sense.
Not so long ago a 25% efficient silicon cell had major market share. Perovskite, so close to 25% just might be on the market launch pad soon.
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By Brian Westenhaus via New Energy and Fuel
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