Organic Ion Template‐Guided Solution Growth of Ultrathin Bismuth Oxyselenide with Tunable Electronic Properties for Optoelectronic Applications

Abstract

2D Bi2O2Se has recently attracted widespread research interest due to its high electron mobility and good air stability with tunable bandgap. However, the direct and controllable growth of large‐size, high‐quality ultrathin Bi2O2Se with tunable electronic properties remains a great challenge. Here, an organic ion template‐guided solution growth method, is developed using water as a solvent to efficiently obtain high‐quality 2D Bi2O2Se. Significantly, the thicknesses and morphologies of 2D Bi2OxSe with various oxygen deficiencies; are also achieved. Optical spectroscopic results indicate that oxygen defects can dramatically tune the electronic properties of Bi2O2Se, such as work function, band gap, and energy‐band positions. As a result, the optimized Bi2O2Se devices exhibit a high photoresponsivity of 842.91 A W−1, photo‐detectivity of 8.18 × 1012 Jones under 532 nm laser, and electron mobility of 334.7 cm2 V−1 s−1. This work proposes a new green solution method to synthesize large‐sized, high‐quality Bi2O2Se with tunable electronic structures that can be extended for various applications and provides a new possibility of transfer‐free large‐scale device manufacturing.

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi2O2Se/MoS2 Type-II Heterojunction

“…Previous studies reported that the theoretical work function of Bi 2 O 2 Se is 4.23 eV (2 Layer) and 4.15 eV (1L), whereas the experimental value varies between 4.37 and 4.45 eV. − In contrast, we find the work function of Bi 2 O 2 Se as 5.485 eV, which is much higher. This is attributed to the trapping of the electron in the defect states in Bi 2 O 2 Se and the corresponding movement of the Fermi level away from the conduction band minimum ( E CBM ) and, thus, the increase in work function . Similarly, the work function of 1L-MoS 2 is 4.435 eV, as reported in our previous study …”

Defect-induced photogating effect and its modulation in ultrathin free-standing Bi2O2Se nanosheets with a visible-to-near-infrared photoresponse

“…66 In the NS with defects, the work function is higher than for the pure Bi 2 O 2 Se bulk, and the Fermi level moves away from the CB, suggesting that the nanosheet becomes less n-type, which is attributed to defect-induced trapping. 67 To explain the PNPC effect, we propose the band diagrams shown in Fig. 5d–f that illustrate the different processes taking place in the absence and presence of light.…”

Rapid Detection of Trace Nitro-Explosives under UV Irradiation by Electronic Nose with Neural Networks

“…To further explore the band structure of the SnO 2 and WO 3 , UV–vis and the small binding energy range scan of VB-XPS were carried out to obtain the band gap ( E g ), conduction band ( E c ), and valence band ( E v ). The band gap was calculated by the Tauc plot method, as shown in Figure S6a, b, and the E g values of SnO 2 and WO 3 are 3.31 and 2.85 eV, respectively. Figure S6c,d shows the VB-XPS results of SnO 2 and WO 3 ; Δ V is the distance between the two inflection points of the curve, and it is also equal to the distance from the top of the E c to the Fermi level; meanwhile, the work function (Φ) and Δ V have the following relationship: Δ V = Φ - ψ, ψ is the work function of the XPS analyzer. , As a result, the E c and E v of SnO 2 and WO 3 were calculated to be −4.45 and −7.76, −3.99, and – 6.84 eV, respectively.…”

“…The band gap was calculated by the Tauc plot method, as shown in Figure S6a, b, and the E g values of SnO 2 and WO 3 are 3.31 and 2.85 eV, respectively. Figure S6c,d shows the VB-XPS results of SnO 2 and WO 3 ; Δ V is the distance between the two inflection points of the curve, and it is also equal to the distance from the top of the E c to the Fermi level; meanwhile, the work function (Φ) and Δ V have the following relationship: Δ V = Φ - ψ, ψ is the work function of the XPS analyzer. , As a result, the E c and E v of SnO 2 and WO 3 were calculated to be −4.45 and −7.76, −3.99, and – 6.84 eV, respectively. Then, the differences in E c (Δ E c ) and E v (Δ E v ) between SnO 2 and WO 3 are 0.46 and 0.92 eV, respectively.…”