2D Organic/Inorganic Hybrid Perovskites

Organohalide perovskites have generated broad interest in recent years because of their potential for use in optoelectronic devices (e.g., solar cells, light emitting diodes, and detectors). On the other hand, organohalide perovskite quantum wells initially drew attention because of their extraordinary electronic structures. Photoexcited electron-hole pairs, termed excitons, are quantum-confined in these systems because the thicknesses of the 2D quantum wells are smaller than the sizes of the excitons. As in other quantum-confined systems, the optical band gaps in 2D perovskites can be tuned with control over the thicknesses of the quantum wells. One emerging area of research involves layered systems that possess 2D quantum wells with various thicknesses. Interesting results have emerged, including solar cells with high efficiency and much improved stability compared with 3D perovskites based ones, and light-emitting devices with high efficiencies.

In previous studies, the organic layers between lead-halide quantum wells primarily act as insulating dielectrics. The Coulombic couplings that drive energy transfer between neighboring quantum wells, which are separated by approximately 0.7 nm, are relatively weak (less than kBT at ambient conditions). For this reason, we recently developed layered 2D perovskites with functional organic cations whose electronic states more readily mix with those of the quantum wells, thereby promoting transport of electrons between quantum wells. With these designed functional organic cations, we are actively investigating how these functional organic cations would change the optoelectronic properties of these materials, aiming to achieve hybrid materials with novel properties, and disclose rigorous structure-property correlations to guide further design. This is a highly interdisciplinary research area, where the collaboration with many other groups is essential.

Below are recent publications from our group in this area.

General Reviews:

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• Adv. Mater. 2018, 1802041

  • https://doi.org/10.1002/adma.201802041

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Functional Organic Cations:

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• ACS Appl. Mater. Interfaces 2018, 10, 33187−33197

  • https://doi.org/10.1021/acsami.8b10230

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• J. Am. Chem. Soc. 2019, 141, 7955−7964

  • https://doi.org/10.1021/jacs.9b02909

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• Nature Communications 2019, 10, 1276

  • https://doi.org/10.1038/s41467-019-08980-x

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• J. Am. Chem. Soc., 2019, 141, 5972–5979

  • https://doi.org/10.1021/jacs.9b00972

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• ACS Materials Lett. 2019, 1, 171-176

  • https://doi.org/10.1021/acsmaterialslett.9b00102