We demonstrated the first solar cell made from perovskite quantum dots (QDs), which are also the highest efficiency all-inorganic perovskite devices reported in the literature. Using all-inorganic components can help solve the instability challenge of perovskite materials that have an organic A-site cation. Cs+ has been explored as a replacement for the A-site organic cation, but due to a low Goldschmidt tolerance factor bulk CsPbI3 crystalizes in the orthorhombic phase, which has an unsuitably high bandgap for use in photovoltaics. We find that the high-temperature cubic phase is stabilized in QDs at room temperature due to the surface strain and report a purification method using methyl acetate that produces colloidally stable CsPbI3 QDs. The cubic phase can be preserved through the fabrication of conductive films and the resulting solar cells perform in ambient. While QD solar cells typically have a large VOC deficit compared to bulk materials, the perovskite QDs exhibit the highest VOC of any material with a bandgap below 2 eV (aside from III-Vs).

Phase-stabilized α-CsPbI3 quantum dots and fabrication of all-inorganic perovskite devices

253rd National Meeting (2017)

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