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 found an effective chemistry solution that successfully merges the device efficiency qualities of 3D perovskite with the stability qualities of 2D perovskite to create a mixed 2D-3D perovskite that yields both tremendous performance capability and stability. The novel approach is based on the incorporation of cation phylethylammonium (PEA+) and anion thiocyanate (SCN-) additives into the perovskite precursor ink. The synergistic coupling of PEA+ and SCN- forms a mixed hybrid 3D perovskite crystal structure blended with 2D (or quasi-2D) perovskite crystal structure located primarily at/near the layer surfaces and grain boundaries. These enhancements of the perovskite crystallinity lead to passivation of defect densities and energy disorders at the surface and enable markedly improved charge carrier mobility and lifetime.
Such stability enhancements are applicable to a wide range of perovskite compositions and produce dramatic, improvements to overall power conversion efficiency (PCE) of the layers, particularly when combined as a wide-bandgap top-layer in tandem with other photovoltaic devices such as CIGS or Si based layers. For instance, a perovskite/CIGS tandem device where the perovskite layer utilized the hybrid 3D-2D structure identified here achieved an overall device performance exceeding 26%.
This technology is within the Film Chemistry 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 licensing executive Bill Hadley at Bill.Hadley@nrel.gov.
Applications and Industries
- Tandem photovoltaic devices
- Improvements to optoelectronic properties of perovskite films
- Stability enhancements for perovskite layers in tandem PV devices