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.
Perovskite photovoltaic devices are composed of organic and inorganic moieties that make developing energetically-favorable contacts for electron and hole extraction challenging. One material that has shown promise as a hole contact layer for perovskite devices, and has been commonly used within research devices, is NiOx. However, recent NREL experiments have demonstrated that the pulsed-laser deposition method commonly used to deposit NiOx generates the contaminant oxy-iodo (IO3-) species that binds positively charged methylammonium (MA) cations and negatively impacts overall device performance.
Thus, NREL researchers have developed novel processing parameters for atomic layer deposition (ALD). These processing parameters enable the deposition of NiOx films, and other oxide films, on top of perovskite absorber layers (MAPbI3 or FAPbI3) and eliminate the generation of the contaminant oxy-iodo (IO3-) species during oxide film deposition.
This technology is within the Hole and Electron Extraction Layer Engineering group of NREL’s perovskite portfolio. For further information regarding NREL's broader perovskite portfolio, please visit NREL's Perovskite Patent Portfolio website.
To learn more about Oxide Interlayers for Perovskite Photovoltaics, please contact Bill Hadley at Bill.Hadley@nrel.gov.
Applications and Industries
- Avoids the generation of contaminant IO3-
- Improves charge carrier collection