Optical and structural properties of Er2O3–ErOOH powder grown by chemical bath

Photoluminescent Green Emission Band Induced by the Systematic Change of -CH3, -OCH3 and Naphthyl Groups in Chiral Imines

“…The optical behavior associated with electronic transitions appearing in these organic molecules was also examined. In this report, we apply the model used to investigate electronic transitions in semiconductors, oxides, and some dielectrics materials . The near-edge region can be fitted in an equation in which the intercept gives the band gap energy ( E g ) and the fitting exponent can be associated with the electronic transition as direct or indirect, and are called Tauc plots .…”

Experimental and DFT Study of the Photoluminescent Green Emission Band of Halogenated (−F, −Cl, and −Br) Imines

“…Applying the absorbance experimental results, the E g of the samples was calculated. The optical behavior associated with electronic transitions appearing in these organic molecules was also examined, applying the model used to investigate electronic transitions in semiconductors [38,54], oxides [14], and some dielectrics materials [55]. A typical model to quantify the E g for a direct band is the classic Tauc model, which is simple, versatile, and very powerful to provide adequate experimental results in different energy intervals of the photon (hν).…”

“…PL reports have identified visible-region bands located at ~450–800 nm (~2.7–1.5 eV) due to interstitial defects, vacancies, etc., in some inorganic crystals. In some rare earth oxides, the emission bands located in the UV-Vis region are associated with electronic transitions of the f→f orbitals [14]. The PL spectra at room temperature for I and I − X crystals is shown in Figure 10, displaying emission bands for I located at ~599 nm (~2.13 eV), I − F : ~568 nm (~2.18 eV), I − Cl : ~553 nm (~2.24 eV), and I − Br : ~599 nm (~2.07 eV), respectively.…”

“…Such reports and our own research have demonstrated that face-to-face intermolecular π→π* interactions can have a dramatic impact on the PL properties of organic materials and lead to shifts of emission spectra due to excimer emission formation [63,64]. Thus, the emission bands in the visible region can be associated with the crystalline defects that are generally observed in visible region for other types of materials, such as semiconductors and rare earth oxides [14]. The PL spectra of the I − Cl crystal is shown in Figure 11.…”

“…These bands are associated with crystalline defects such as vacancies and interstices. However, they have been also observed in rare earth oxides and these are associated with f → f transitions [14]. The introduction of functional groups in I crystals causes a PL signal increase of the characteristic emission peaks of I [15] by mesomeric and inductive effects, as the electron density of the aromatic ring is increased with the π→π* and n → π* electronic transitions, etc., along with hyperconjugation [16].…”