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Watering (Perovskite) Solar Cells Makes Them Grow… in Power!
http://www.oist.jp/news-center/news/2016/7/27/watering-solar-cells-makes-them-grow%E2%80%A6-power[font face=Serif]27 Jul 2016
[font size=5]Watering Solar Cells Makes Them Grow… in Power![/font]
[font size=3]Perovskite solar cells are the rising star in the photovoltaic landscape. Since their invention, less than ten years ago, their efficiency has doubled twice and it is now over 22% – an astonishing result in the renewable energy sector. Taking the name ‘perovskite’ from the light-harvesting layer that characterizes them, these solar cells are lighter, cheaper, and more flexible than the traditional crystalline silicon-based cells.
Perovskite solar cells are usually exposed to ambient air for several hours after fabrication. This procedure increases their efficiency, even if the reason behind the phenomenon was unclear. The scientific explanation of this practice has now been discovered by researchers from the Energy Materials and Surface Sciences Unit (EMSS) at the Okinawa Institute of Science and Technology Graduate University (OIST) led by Prof Yabing Qi. Their results are published in Advanced Materials Interfaces.
…
The scientists performed controlled exposure of the hole transport layer to environmental gasses, focusing on oxygen, nitrogen, and moisture – water that is in a gas state. Then, they checked the electrical properties of the hole transport layer, using a variety of methods, to see if and how the inside of the transport layer changed. “What we found is that oxygen and nitrogen do not have any role in the redistribution of the dopants,” Hawash explained. “But in the case of moisture, the solar cells’ efficiency increases. This is the discovery: moisture is the air component that causes the redistribution of the dopant across the material, and thus the enhancement of the electric properties of the solar cells.”
The scientists explain this phenomenon with the structure of the transport layer, which has many pinholes that allow the passage of gasses between the ambient and the underneath material. The dopant in the transport layer is a salt – Lithium TFSI. Being a salt, the dopant has a hygroscopic nature: it absorbs water. When the solar cells are exposed to moisture, the water absorbed by the transport layer causes the dopant to redistribute. However, long time exposure to moisture has a detrimental effect on the solar cells.
…[/font][/font]
[font size=5]Watering Solar Cells Makes Them Grow… in Power![/font]
[font size=3]Perovskite solar cells are the rising star in the photovoltaic landscape. Since their invention, less than ten years ago, their efficiency has doubled twice and it is now over 22% – an astonishing result in the renewable energy sector. Taking the name ‘perovskite’ from the light-harvesting layer that characterizes them, these solar cells are lighter, cheaper, and more flexible than the traditional crystalline silicon-based cells.
Perovskite solar cells are usually exposed to ambient air for several hours after fabrication. This procedure increases their efficiency, even if the reason behind the phenomenon was unclear. The scientific explanation of this practice has now been discovered by researchers from the Energy Materials and Surface Sciences Unit (EMSS) at the Okinawa Institute of Science and Technology Graduate University (OIST) led by Prof Yabing Qi. Their results are published in Advanced Materials Interfaces.
…
The scientists performed controlled exposure of the hole transport layer to environmental gasses, focusing on oxygen, nitrogen, and moisture – water that is in a gas state. Then, they checked the electrical properties of the hole transport layer, using a variety of methods, to see if and how the inside of the transport layer changed. “What we found is that oxygen and nitrogen do not have any role in the redistribution of the dopants,” Hawash explained. “But in the case of moisture, the solar cells’ efficiency increases. This is the discovery: moisture is the air component that causes the redistribution of the dopant across the material, and thus the enhancement of the electric properties of the solar cells.”
The scientists explain this phenomenon with the structure of the transport layer, which has many pinholes that allow the passage of gasses between the ambient and the underneath material. The dopant in the transport layer is a salt – Lithium TFSI. Being a salt, the dopant has a hygroscopic nature: it absorbs water. When the solar cells are exposed to moisture, the water absorbed by the transport layer causes the dopant to redistribute. However, long time exposure to moisture has a detrimental effect on the solar cells.
…[/font][/font]