RETRACTED: Two-Dimensional Violet Phosphorus P₁₁: A Large Band Gap Phosphorus Allotrope

Abstract

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 P11 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-P11 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-P11, violet-P21, and fibrous-P21 are discussed. The violet-P11 crystals can be mechanically exfoliated down to a few layers (∼6 nm). Photoluminescence and Raman measurements reveal the thickness-dependent nature of violet-P11, and exfoliated violet-P11 flakes were stable in ambient air for at least 1 h, exhibiting moderate ambient stability. The bulk violet-P11 crystals exhibit excellent stability, being stable in ambient air for many days. The optical band gap of violet-P11 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-P11 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.

Renaissance of elemental phosphorus materials: properties, synthesis, and applications in sustainable energy and environment

“…Very recently, Cicirello and colleagues synthesized a new two-dimensional allotrope of violet phosphorus, dubbed violet-P 11 , using a salt flux method in the presence of bismuth. 136 The crystal structure of this allotrope from different views is shown in Fig. 7f.…”

“…Single-crystal XRD has revealed that violet-P 11 crystallizes in the monoclinic space group C2/c (15), with unit cell parameters of 9.166(6), 9.121 (6), and 21.803( 14) Å for a, b, and c, respectively. 136 Violet-P 11 exhibits substantial stability in ambient air even after being exfoliated for at least an hour.…”

Type‐II Red Phosphorus: Wavy Packing of Twisted Pentagonal Tubes

“…[3][4][5][6][7] Moreover, previous theoretical calculations and experiments indicated the presence of numerous unexplored phosphorus polymorphs. [6,[8][9][10][11][12][13][14][15][16][17] Considering that various forms of phosphorus crystals have recently emerged as platforms for investigating unique electronic and optical properties in low dimensions, [18][19][20][21][22] the identification of a new structural phase of elemental phosphorus will be of critical importance to better design materials for various applications.…”

“…[2] The crystal structure of type-V RP (violet or Hittorf's phosphorus) has been identified using single-crystal XRD [23] in 1966 and has recently attracted increasing research interest. [15][16]24] The crystal structure of type-IV RP (fibrous phosphorus) has been identified in a relatively recent study. [25] Both types-IV and V RP contain a tubular motif [P8]P2[P9]P2[ in their structures.…”

Type‐II Red Phosphorus: Wavy Packing of Twisted Pentagonal Tubes

“…[3][4][5][6][7] Moreover, previous theoretical calculations and experiments indicated the presence of numerous unexplored phosphorus polymorphs. [6,[8][9][10][11][12][13][14][15][16][17] Considering that various forms of phosphorus crystals have recently emerged as platforms for investigating unique electronic and optical properties in low dimensions, [18][19][20][21][22] the identification of a new structural phase of elemental phosphorus will be of critical importance to better design materials for various applications.…”