| Work Detail |
A research team in China has combined solar power generation from a thin layer of kesterite with an electrochromic window of nickel-cobalt bimetallic oxide (NiCoO2).
Researchers led by Henan University (China) have used kesterite thin-film solar cells (CZTSSe) in a new prototype of a smart solar window.
“Our prototype combines a nickel cobalt bimetal oxide (NiCoO2) electrochromic window with CZTSSe thin-film solar cells,” Guofa Cai, lead author of the research, told pv magazine . "This embedded prototype not only realizes the integration of functions of self-powering and intelligent adjustment of solar radiation, but also extends its function to energy storage."
The scientists constructed the solar cell with a molybdenum (Mo)-coated glass substrate, the kesterite absorber, a cadmium sulfide (CdS)-based buffer layer, a zinc oxide (ZnO) layer, a indium and tin (ITO) deposited by magnetron sputtering and silver (Ag) metal contacts.
They used a simple chemical bath deposition (CBD) strategy to prepare the electrochromic NiCoO2 window films. “Due to the porous structure of nanoscales and the synergistic effect of nickel and cobalt elements, NiCoO2 film and NiCoO2-based electrochromic smart windows exhibit excellent electrochemical, electrochromic, and energy storage performance,” Cai explains.
The window also integrates a titanium oxide (TiO2) counter electrode film with reputedly excellent electrochromism and energy storage performance. This nanoparticle film acts as an ion storage layer due to its good charge balancing ability and high transmittance.
Tested under standard lighting conditions, the solar window showed an energy consumption of 318.3 mWh/m2 and an overall efficiency of 2.15%, comparable values, according to the team, with most solar windows developed to date.
"In particular, thanks to the porous structure of nanospheres and the synergistic bimetallic effect, NiCoO2 electrochromic films exhibit high optical modulation, fast switching speed, outstanding electrochromic stability, and excellent speed capability," they explained.
“The solar irradiation management performance of self-powered smart windows with neutral color tint has been studied for the first time, which is beneficial in improving occupant comfort and gives it great potential in architectural applications,” said Cai. .
The cell technology and window design were presented in the article “ Multi-functional electrochromic energy storage smart window powered by CZTSSe solar cell for intelligent managing solar radiation of building ”. solar CZTSSe for intelligent management of building solar radiation), published in Solar Energy Materials and Solar Cells .
Kesterite is one of the most promising light-absorbing materials for possible use in low-cost thin-film solar cells. Kesterites are made up of common elements, such as copper, tin, zinc, and selenium. And unlike GIGS compounds, no supply bottlenecks are anticipated in the future. However, kesterite is still less efficient than CIGS in mass production. The world record for efficiency of this type of cells is 12.6%, achieved by the Japanese thin-film producer Solar Frontier in 2013.
Smart windows and photovoltaic devices (PVCD) are able to allow adjustable transparency glazing and, at the same time, generate electricity through the photovoltaic effect. This technology has so far been applied to the design of self-powered smart windows for buildings and vehicles at the research level; however, it is still in a very early stage of development. The ability to modulate interior light and heat transmission, while generating power from the PVs, is enticing for future BIPV developments. |
