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Energy-Harvesting Chromogenic Devices

Stage: Development

Perovskite photovoltaics are a new class of light absorbers with exceptional and unparalleled progress in solar power performance. A perovskite is any material with a specific ABX3 crystal structure. In photovoltaic applications, the A cation can be either organic, inorganic, or hybrid in composition. The B component is typically a metal cation such as lead, and X is a halide such as iodine or bromine. Work on solar cells using perovskite materials has advanced rapidly as a result of the material’s excellent light absorption, charge-carrier mobilities, and lifetimes – resulting in high device efficiencies with low-cost, industry-scalable technology. While the potential for perovskite photovoltaic devices is high, commercialization will require overcoming other challenges relating to material stability, efficiency, and environmental compatibility.

Researchers at NREL have developed a perovskite photovoltaic device that reversibly switches between a transparent and tinted state. In its first state the device is transparent and converts only non-visible spectrum light to current. When the device is sufficiently heated (i.e. in direct sunlight) its crystalline phase changes and it absorbs the visible portion of the solar spectrum, effectively becoming tinted. This invention is a significant step towards the economical production of solar windows that dynamically modulate absorption and transmission properties while converting sunlight into usable electricity.

This technology is within the Device Architecture category of NREL’s perovskite portfolio. For further information regarding NREL's broader perovskite portfolio, please visit NREL's Perovskite Patent Portfolio website.

For more information on Energy-Harvesting Chromogenic Devices, please contact Bill Hadley at Bill.Hadley@nrel.gov.

Applications and Industries

  • Smart windows
  • Building integrated photovoltaics
  • Commercial and residential buildings


  •  Switchable between light absorbing and transparent states
  •  Photovoltaically active in both absorbing and transparent state
  •  Tunable switching temperature