Oxygen-vacancy and depth-dependent violet double-peak photoluminescence from ultrathin cuboid SnO2 nanocrystals

Abstract

A double peak in the violet region between 360 and 400 nm is observed from the photoluminescence spectra acquired from cuboid SnO2 nanocrystals and the energy separation between the two subpeaks increases with nanocrystal size. The phenomenon arises from band edge recombination caused by different in-depth distributions of oxygen vacancies (OVs). Density functional theory calculations disclose that variations in the oxygen vacancies with depth introduce valence-band peak splitting leading to the observed splitting and shift of the double peak.

Influence of in-plane and bridging oxygen vacancies of SnO2 nanostructures on CH4 sensing at low operating temperatures

“…16 DFT calculations using generalized gradient approximation (GGA) also predicted luminescence transitions around 2 and 2.4 eV which were attributed to the bridging and the in-plane "O" vacancies, respectively. 4 By using 17 showed that the in-plane "O" vacancies were responsible for shallow donor states while the bridging "O" vacancies were to form relatively deeper states. Dutta and Bahadur 18 reported luminescence at 2.4 eV for SnO 2 quantum dots due to singly charged inplane "O" vacancies which were probed independently using electron spin resonance technique.…”

Brush-like SnO2/ZnO hierarchical nanostructure: Synthesis, characterization and application in UV photoresponse

“…The oxygen vacancies can form acceptor level which results in a blue emission band at 445 nm. 37 As for the SnO 2 /ZnO hierarchical structure, the PL spectrum is dramatically different from that of the SnO 2 nanowires. The PL spectrum in Fig.…”

“…The lower energy at 530.1 eV corresponds to O 2− in the structure of regular rutile SnO 2 , the binding energy at 531.9 eV can be ascribed to the oxygen vacancies on the SnO 2 nanowire surface. [35][36][37][38][39] The above XPS result indicates the existence of oxygen vacancy defects which will play crucial role in the PL of SnO 2 nanowires. The SEM images of eventually formed SnO 2 /ZnO hierarchical nanostructure are shown in Figure 3(a) and 3(b), the nanostructures have brush-like morphology with a high surface-volume ratio.…”

“…The binding energy of the Sn 3d 5/2 and Sn 3d 3/2 are located at 486.2 eV and 494.7 eV. 37 The spectrum of O1s shows an asymmetric shape which can be deconvoluted into two subpeaks at binding energies of 530.1 and 531.9 eV. The lower energy at 530.1 eV corresponds to O 2− in the structure of regular rutile SnO 2 , the binding energy at 531.9 eV can be ascribed to the oxygen vacancies on the SnO 2 nanowire surface.…”

Regulation of oxygen vacancy types on SnO2 (110) surface by external strain

“…[1][2][3][4][5] However, their properties depend heavily on the nanostructure morphology as well as electronic structure, which is modified by intrinsic oxygen vacancies (OVs). 6,7 Development of optoelectronic encompassing bulk SnO 2 materials, for instance, has been hampered by its dipole forbidden nature. 8,9 Fortunately, owing to the existence of OVs, changes in symmetry of nanostructures related with surface states may allow direct possible.…”