Skyscrapers are a common and popular sight in cities. They are favored for their ability to house many people and activities within a bounded area, magnifying land use while contributing to sustainable development. Soon, we will say goodbye to traditional skyscrapers, as they will be transformed into huge batteries. The new skyscrapers are already being tested in one state and could reform the contribution to sustainable development in urban landscapes.
Skyscrapers are being transformed into huge batteries
Skyscrapers are being transformed into huge batteries, and thanks to a team led by the University of Michigan, the research set a new efficiency record for color-neutral, transparent solar cells. This achievement was reached by using an organic, or carbon-based, design rather than traditional silicon. The solar cells might have a slight green tint, but the real color is more like the gray of sunglasses and car windows.
Windows are on the face of every skyscraper, which makes them the perfect location for organic solar cells. According to Stephen Forrest, the Peter A. Franken Distinguished University Professor of Engineering, and Paul G. Goebel Professor of Engineering, the team chose organic cells because, unlike silicon, they offer a combination of extreme efficiency and extremely visible transparency.
This is how these huge batteries reform urban sustainability
The curtain walls of skyscrapers usually have a coating on them to reflect and absorb sunlight in the visible and infrared spectrum. This is to reduce the brightness and heat inside the skyscraper. This is seen as a ‘waste’ of energy, which is why transparent solar cells can be useful in opening a new era of energy usage. According to Professor Forrest’s group’s findings in the scientific journal Proceedings of the National Academy of Sciences, some existing windows have transparency that is similar to the solar cells’ transparency.
“The new material we developed, and the structure of the device we built, had to balance multiple trade-offs to provide good sunlight absorption, high voltage, high current, low resistance and color-neutral transparency all at the same time.” – Yongxi Li, assistant research scientist in electrical engineering and computer science.
The solar cells’ material is a mixture of organic molecules designed to be transparent in the visible and absorbing in the near-infrared. Near-infrared is an invisible part of the spectrum that accounts for much of sunlight’s energy. The research team also developed visual coatings to enhance the power produced from infrared light, as well as the transparency in the visible range. Normally, the two qualities compete with one another.
The marvelous efficiency of transparent solar cells
Transparent solar cells are assessed by their efficiency in using light. Light-using efficiency indicates how much energy from the light hitting the window is available in the form of electricity or as transmitted light on the interior side. Past transparent solar cells have light-using efficiencies of 2% to 3%.
The color-neutral version was produced with an indium tin oxide electrode, which had an efficiency of 3.5%. A silver electrode increased light-using efficiency to 10.8% with 45.8% transparency; however, due to its slight green tint, it may not be acceptable in some window applications. Both organic solar cell versions can be produced at a large scale with materials that are less toxic than other transparent solar cells and can be placed between the panes of double-glazed windows. They can also be custom-made for local latitude, benefiting from the high efficiency when the sun’s rays strike them at 90 degrees.
As Forrest’s team works on improving this innovative technology, existing skyscrapers could be transformed sooner than we think, with new “huge batteries” popping up all over urban areas. Sustainable development in urban settings is becoming more efficient by the day, and soon cities all over will benefit from the power of renewable energy resources.