Highly efficient photoelectric effect in halide perovskites for regenerative electron sources

Liu, Fangze; Sidhik, Siraj; Hoffbauer, Mark A.; Lewis, Sina G.; Neukirch, Amanda; Pavlenko, Vitaly; Tsai, Hsinhan; Nie, Wanyi; Even, Jacky; Tretiak, Sergei; Ajayan, Pulickel M.; Kanatzidis, Mercouri G.; Crochet, Jared; Moody, Nathan A.; Blancon, Jean-Christophe; Mohite, Aditya

doi:10.1038/s41467-021-20954-6

Cited by 15 publications

(14 citation statements)

References 44 publications

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“…However, once a Cs coating is added, systems containing I and terminated with a [001] surface have the lowest work functions. These results are in good agreement with the recent experimental demonstration of Cs-coated perovskite materials as photocathode devices, 37 and the insights gained here can further be used for material development. A phenomenological model was developed to predict the work function with the material, surface coverage, and surface termination.…”

supporting

confidence: 91%

“…In order to lower the work function into the optical region for more affordable operating conditions, one technique is to add a coating of Cs. Indeed, recently reported efficient free-electron emission halide perovskite thin films operating in the visible to the ultraviolet spectral range for the first time further motivate in-depth computational studies on this emergent application.…”

mentioning

confidence: 96%

“…Here we use density functional theory (DFT) to investigate the photocathode performance of Cs-coated halide perovskites. Many current photocathodes utilize Cs coatings to lower the work functions of photocathode materials due to the low electron affinity of Cs. − In this study, we specifically focus on Cs-coated CsPbX 3 , where X is a halide (Br or I). We consider the influence of surface termination, coating thickness, and material composition on the work function, electronic and optical properties, and Cs adsorption energy of these perovskites.…”

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confidence: 99%

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Cesium-Coated Halide Perovskites as a Photocathode Material: Modeling Insights

Lewis

Ghosh

Jensen

et al. 2021

J. Phys. Chem. Lett.

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Photocathodes emit electrons when illuminated, a process utilized across many technologies. Cutting-edge applications require a set of operating conditions that are not met with current photocathode materials. Meanwhile, halide perovskites have been studied extensively and have shown a lot of promise for a wide variety of optoelectronic applications. Well-documented halide perovskite properties such as inexpensive growth techniques, improved carrier mobility, low trap density, and tunable direct band gaps make them promising candidates for next-generation photocathode materials. Here, we use density functional theory to explore the possible application of pure inorganic perovskites (CsPbBr3 and CsPbI3) as photocathodes. It is determined that the addition of a Cs coating improved the performance by lowering the work function anywhere between 1.5 and 3 eV depending on the material, crystal surface, and surface coverage. A phenomenological model, modified from that developed by Gyftopoulos and Levine, is used to predict the reduction in work function with Cs coverage. The results of this work aim to guide the further experimental development of Cs-coated halide perovskites for photocathode materials.

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confidence: 91%

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confidence: 96%

mentioning

confidence: 99%

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Cesium-Coated Halide Perovskites as a Photocathode Material: Modeling Insights

Lewis

Ghosh

Jensen

et al. 2021

J. Phys. Chem. Lett.

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“…Coating perovskite surfaces with a metal like Cs presents potential technological promises in applications requiring electron sources such as electron beam accelerator facilites. 28 It has recently been demonstrated that by depositing monolayers of Cs on top of halide perovskites, the electron emission efficiency was improved 29 and the improvement was attributed to a change of sign of the electron affinity, which translates into a diminishing work function. 1).…”

Section: Effect Of the Surface Coating With Csmentioning

confidence: 99%

A Theoretical Framework for Microscopic Surface and Interface Dipoles, Work Functions, and Valence Band Alignments in 2D and 3D Halide Perovskite Heterostructures

et al. 2021

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We propose a computational methodology that highlights the intimate connection between surface and interface dipoles and work functions or valence band alignments.We apply the methodology to inspect the energy level alignments of halide perovskites and explore various situations relevant to perovskite-based heterostructures: i) the effect of surface termination, the ability to fine-tune and interpret the shift in energy alignments via ii) surface coating and iii) surface functionalization and / or passivation with molecules. We highlight the importance of local strain relaxation at the surfaces or interfaces, and revisit classical approaches based on capacitor models. Finally, we show that surface dipoles are additive in heterostructures and illustrate it through a 2D/3D perovskite interface. This provides a handy tool to interpret band alignments in complex perovskite-based heterostructures and buried interfaces. The scope of our work goes far beyond halide perovskites and can be useful to scrutinize the surfacial and interfacial behaviors of other semiconductors and heterojunctions. It allows bridging results from atomistic ab initio calculations and classical simulation approaches for multilayered thin film devices.

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“…The photoelectric effect 1 describes the response of molecules and materials to electromagnetic radiation by emission of electrons. This effect plays a fundamental role in daily life, but also in cutting-edge technology, such as optoelectronic devices, 2,3 regenerative electron sources for free-electron lasers, 4 or photovoltaics, for instance to design artificial ion pumps that mimic nature. 5 …”

Section: Introductionmentioning

confidence: 99%