Smart photovoltaic windows represent a promising green technology featuring tunable transparency and electrical power generation under external stimuli to control the light transmission and manage the solar energy. Berkeley Lab researchers led by Peidong Yang have demonstrated a thermochromic solar cell for smart photovoltaic window applications utilizing the structural phase transitions in inorganic halide perovskite caesium lead iodide/bromide. The solar cells undergo thermally-driven, moisture-mediated reversible transitions between a transparent non-perovskite phase (81.7% visible transparency) with low power output and a deeply colored perovskite phase (35.4% visible transparency) with high power output. The inorganic perovskites exhibit tunable colors and transparencies, a peak device efficiency above 7%, and a phase transition temperature as low as 105 °C. The technology promises excellent device stability over repeated phase transition cycles without color fade or performance degradation. The photovoltaic windows showing both photoactivity and thermochromic features represent key stepping-stones for integration with buildings, automobiles, information displays, and potentially many other technologies. For details of this perovskite phase transition technology, see the researchers’ Nature publication, linked below.
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Lin, J., Lai, M., Dou, L., Kley, C., Chen, H., Peng, F., Sun, J., Lu, D., Hawks, S., Xie, C., Cui, F., Alivisatos, A., Limmer, D., Yang, P. “Thermochromic halide perovskite solar cells,” Nature Materials, Vol. 17, March 2018, 261-267.