Synthesis of methylammonium lead iodide perovskite films via cation exchange of melt-processed films for photovoltaic applications
Summary: Iowa State University and Ames Laboratory researchers have developed a new method of making perovskite thin films for an absorber layer in photovoltaic cells.Description: Perovskite solar cells have been an area of interest in emerging solar technologies since 2009. With certified power conversion efficiency (PCE) increasing from about 1% to its current state of 22.7% in 8 years, perovskite cells have become competitive with current silicon based solar cells’ PCE. However, whereas silicon based solar cells are a mature technology that haven't seen significant PCE increases in years, perovskites continue to show improvement. Additionally perovskite cells offer the advantage of being flexible thin films (with less material being used, potentially saving costs), that are partially transparent. The transparent nature allows for tandem cells, potentially further boosting PCE. Current tandem cells are so prohibitively expensive that their use has been limited to niche applications such as the aviation industry (where the main cost driver is weight/cost of fuel). The low cost of perovskites offers the possibility of tandem cells that are competitive on a cost/watt basis with single crystal Si.Typical processing techniques of organolead mixed halide perovskites require dissolution of the individual single halide species before deposition of thin films (most commonly by spin coating or film casting). The precipitated species have questionable homogeneity and require regulated VOCs. These “air toxic” solvents have been a limiting factor for scale-up. By melt processing at fairly low temperature (currently 250 °C), costs could be reduced and scale-up becomes more feasible. Iowa State University and Ames Laboratory researchers melt process phenethylammonium lead iodide, or analogous material, and via a simple cation exchange process create films that are promising photovoltaic materials. Advantage: • Low temperature synthesis • Limited harmful solvents • Amenable to scale-up Application: Tandem solar cell, perovskite solar cells Desc0000.png Stage1.png Development Stage
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