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 developed a process for creating a new class of lead halide perovskite material that exhibits high open circuit voltage (VOC) with very low loss in comparison to identical thin film perovskite photovoltaic devices. The process involves routine synthesis of two compositions of perovskite quantum dots (formamadinium lead triiodide (FAPbI3) and cesium lead triiodide (CsPbI3)) which are then mixed together in desired amounts and heated in order to activate a cation-exchange reaction, resulting in mixed-cation (FAxCs1-x)PbI3 perovskite quantum dots.
(FAxCs1-x)PbI3 perovskite quantum dots made in this process have two distinct advantages. First, synthesis of previously-unachievable (FAxCs1-x)PbI3 quantum dots with >50% Cs incorporation is now available, thus expanding the range of bandgaps, size, and material properties available in the (FAxCs1-x)PbI3 material system. Secondly, (FAxCs1-x)PbI3 quantum dots synthesized by this process exhibit open-circuit voltages approaching 90% of the theoretical thermodynamic limit, compared to ~ 70% for identical materials synthesized by other means. This opens the door to exceptionally well-performing (FAxCs1-x)PbI3 quantum dot photovoltaic devices and optoelectronic structures.
This technology is within the Film Chemistry category of NREL’s perovskite portfolio. For further information regarding NREL's broader perovskite portfolio, please visit NREL's Perovskite Patent Portfolio website.
Contact: Bill Hadley at Bill.Hadley@nrel.gov
Applications and Industries
- Quantum Dots
- Higher efficiency and open circuit voltage VOC than thin film perovskite materials.
- Full range band gap tunability
- Great improvements for thermal stability.