RETRACTED ARTICLE: Surface Passivation of CdSe Quantum Dots in All Inorganic Amorphous Solid by Forming Cd1−xZnxSe Shell

Abstract

CdSe quantum dots (QDs) doped glasses have been widely investigated for optical filters, LED color converter and other optical emitters. Unlike CdSe QDs in solution, it is difficult to passivate the surface defects of CdSe QDs in glass matrix, which strongly suppress its intrinsic emission. In this study, surface passivation of CdSe quantum dots (QDs) by Cd1−xZnxSe shell in silicate glass was reported. An increase in the Se/Cd ratio can lead to the partial passivation of the surface states and appearance of the intrinsic emission of CdSe QDs. Optimizing the heat-treatment condition promotes the incorporation of Zn into CdSe QDs and results in the quenching of the defect emission. Formation of CdSe/Cd1−xZnxSe core/graded shell QDs is evidenced by the experimental results of TEM and Raman spectroscopy. Realization of the surface passivation and intrinsic emission of II-VI QDs may facilitate the wide applications of QDs doped all inorganic amorphous materials.

Effect of Al2O3 on the formation of color centers and CdSe/Cd1−xZnxSe quantum dots in SiO2–Na2O–ZnO glasses

“…For the almost totally crystallized sample S7, two vibration peaks of 210 and 255 cm −1 were in accord with the longitudinal optical (LO) phonon frequencies of bulk hexagonal CdSe and ZnSe crystals, which was corresponding to the results of TEM analysis (Figure D). It is easy to conclude the peak at 238 cm −1 between 210 and 255 cm −1 for S6(HT) was from the formation of Zn–Cd–Se ternary crystals, which was found and demonstrated previously . While the shoulder near ~200 cm −1 of S6(HT) was attributed to CdSe QDs.…”

“…The interplanar distance in the central area was 0.214 nm, identical to the lattice constant of (110) plane of CdSe crystals with hexagonal structure (JCPDS #77–2307 for CdSe), while the interplanar distance with the same direction in the outer area was 0.205 nm, smaller than the lattice constant of CdSe crystals and between that of CdSe and ZnSe crystals (JCPDS #15‐0105 for ZnSe). According to our previous work, that CdSe/Cd 1− x Zn x Se QDs precipitated in glass matrix after heat treatment. However, when the amount of Al 2 O 3 increased to 3 mol.…”

Understanding the atomic and electronic structures origin of defect luminescence of CdSe quantum dots in glass matrix

“…Models of Cd or Zn atoms bonded to Se atoms were also explored, as physically Zn is employed to fix Se which tends to evaporate when the temperature is high . However, computational results were inconclusive, signifying little possibility of interactions between Cd or Zn atoms and Se, with Cd or Zn is associating from the optimized Cd n Se n QDs when the size was small (Figure ).…”

“…Models of Cd or Zn atoms bonded to Se atoms were also explored, as physically Zn is employed to fix Se which tends to evaporate when the temperature is high. 8 However, computational results were inconclusive, signifying little possibility of interactions between Cd or Zn atoms and Se, with Cd or Zn is associating from the optimized Cd n Se n QDs when the size was small ( Figure S6). In the contrary, there exists a bonding between the added Cd or Zn atom and surface Cd atom when the size was large, which is concordant with Cd-Cd n Se n clusters as discussed earlier ( Figure S2).…”

“…By and large, E gap deceases with increasing QD radius, as does the exciton binding energy which dictates optical properties. 29 Regarding the positions of defects in the DOS and within E gap , we anticipate that those of QDs in a glass matrix 8 will be different from those between QDs and organic ligands in colloidal systems. [17][18][19][20][21][22][23][24][25][26][27][28] To the best of our knowledge, there is few researches focusing on the defect mediated morphology and luminescence property of CdSe QDs in glass matrix.…”