Two-dimensional violet phosphorus P11: A large band gap phosphorus allotrope

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Cicirello, Gary
Wang, Mengjing
Sam, Quynh P.
Hart, James L.
Williams, Natalie L.
Yin, Huabing
Cha, Judy J.
Wang, Jian
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Cicirello, G., Wang, M., Sam, Q. P., Hart, J. L., Williams, N. L., Yin, H., . . . Wang, J. (2023). Two-Dimensional Violet Phosphorus P11: A Large Band Gap Phosphorus Allotrope. Journal of the American Chemical Society, 145(14), 8218-8230.

The discovery of novel large band gap two-dimensional (2D) materials with good stability and high carrier mobility will innovate the next generation of electronics and optoelectronics. A new allotrope of 2D violet phosphorus P was synthesized via a salt flux method in the presence of bismuth. Millimeter-sized crystals of violet-P11 were collected after removing the salt flux with DI water. From single-crystal X-ray diffraction, the crystal structure of violet-P was determined to be in the monoclinic space group C2/c (no. 15) with unit cell parameters of a = 9.166(6) Å, b = 9.121(6) Å, c = 21.803(14)Å, β = 97.638(17)°, and a unit cell volume of 1807(2) Å3. The structure differences between violet-P, violet-P, and fibrous-P are discussed. The violet-P crystals can be mechanically exfoliated down to a few layers (∼6 nm). Photoluminescence and Raman measurements reveal the thickness-dependent nature of violet-P, and exfoliated violet-P flakes were stable in ambient air for at least 1 h, exhibiting moderate ambient stability. The bulk violet-P crystals exhibit excellent stability, being stable in ambient air for many days. The optical band gap of violet-P bulk crystals is 2.0(1) eV measured by UV–Vis and electron energy-loss spectroscopy measurements, in agreement with density functional theory calculations which predict that violet-P is a direct band gap semiconductor with band gaps of 1.8 and 1.9 eV for bulk and monolayer, respectively, and with a high carrier mobility. This band gap is the largest among the known single-element 2D layered bulk crystals and thus attractive for various optoelectronic devices.

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American Chemical Society
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Journal of the American Chemical Society
Volume 145, No. 14
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