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.
In the fabrication of perovskite devices, numerous solutions are used. The most common solvents in these solutions are dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Storing these perovskite solutions in nitrogen in the dark, as is typically done, does not completely inhibit hydrolysis of the perovskite materials. Hydrolysis results in dramatic compositional changes in the subsequent perovskite devices. The changes in solution chemistry lead to a modification of the film stoichiometry, band gap, and structure. Developing scalable, stable precursors for the alloyed metals in perovskites is important not only for laboratory-scale research, but also for the industrial production of perovskites.
Researchers at NREL have created a method of synthesizing metal halide perovskites mechanically to avoid their degradation via hydrolysis in solutions. When precursor salts were ball-milled into a powder they were found to be chemically stable, unlike the solution methods normally used. This method allows the storage of large quantities of stoichiometric precursor materials and enables more consistent, higher performance perovskite devices.
This technology is within the Device Architecture group of NREL’s perovskite portfolio. For further information regarding NREL's broader perovskite portfolio, please visit NREL's Perovskite Patent Portfolio website.
Or contact Bill Hadley, the licensing executive, at Bill.Hadley@nrel.gov.
Applications and Industries
- Enables consistent, high performance perovskite device fabrication
- Allows storage of large quantities of precursor material without degradation