Joseph Manser examines a pair of perovskite solar cells.
Low Cost Solar Power
Perovskite solar cells have been studied intensely only in the past year and a half. During that time, numerous researchers joined the effort, attracted by these cells’ promise to be inexpensive yet high performing.
Almost overnight the conversion efficiency of these cells leaped from just a few percent to more than 16% in current versions. Most of the advances were reported in 2012 and 2013. The fast-paced improvement, which hasn’t shown signs of slowing, coupled with inexpensive materials and preparation methods, prompts physicist Henry Snaith to declare that perovskite solar cells are poised “to break the prevailing paradigm” by combining low cost and excellent performance.
Scientists use the term “perovskite” loosely nowadays to refer to a large class of materials that, like CaTiO3, exhibit ABX3 stoichiometry and adopt the perovskite crystal structure. The perovskites rocking the photovoltaics world these days are organometal trihalides, the most commonly studied of which is CH3NH3PbI3. (CH3NH3 is the A group in ABX3.) The main reason for the excitement is the recent steep rate of improvement in perovskite solar-cell performance.
The simplicity of making solar-cell components via liquid-phase chemical reactions and depositing the materials by methods such as spraying and spin coating may make it possible for solar-cell manufacturers to eventually replace clean rooms and sophisticated manufacturing equipment with simple benchtop processes. But even before manufacturers start building production facilities, the simplicity of perovskite solar-cell assembly is attracting many academic researchers. “Anyone can play,” chemistry professor Prashant Kamat says. The barrier to getting started in this field is low, he explains, because this type of research requires only standard lab equipment.
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