Lidé

Ing. Mgr. Neda Neykova, Ph.D.

Všechny publikace

Peculiarities of erbium incorporation into ZnO microrods at high doping level leading to upconversion and the morphology change. Influence on excitonic as well as shallow donor states

  • Autoři: Buryi, M., Ing. Mgr. Neda Neykova, Ph.D., Ridzoňová, K., Remeš, Z., Děcká, K., Hájek, F., Artemenko, A., Mičová, J., Landová, L., Jakubec, I.
  • Publikace: Applied Surface Science. 2023, 611(Part A), 155651(1)-155651(14). ISSN 0169-4332.
  • Rok: 2023
  • DOI: 10.1016/j.apsusc.2022.155651
  • Odkaz: https://doi.org/10.1016/j.apsusc.2022.155651
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Heavily Er-doped zinc oxide (ZnO) microrods with nominal compositions, ZnO:Er(2, 10, 30%), wereprepared by the hydrothermal growth method. The crystallographic phases present in the as grown and annealed materials were determined. The presence of the hexagonal Wurtzite ZnO phase in the form of the hexagonal shape nanoplatelets and microrods was confirmed. Moreover, the Er2O3 phase in the form of nanosheets has been revealed as well. Erbium is partly incorporated into the ZnO hosts. It was thinning upon erbium doping level contributing to erbium oxide. This effect was even more pronouncedupon annealing in air. Moreover, the influence of erbium doping and annealing on paramagnetic shallow donor centers has been studied.

Correlating light-induced deep defects and phase segregation in mixed-halide perovskites

  • DOI: 10.1039/D2TA03538C
  • Odkaz: https://doi.org/10.1039/D2TA03538C
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Mixed-halide perovskites are highly promising materials for tandem solar cells. The phenomenon of phase segregation, however hinders their application. Here, we combine Fourier-Transform photocurrent spectroscopy with photoluminescence and current density–voltage (J–V) measurements to study the effect of light soaking on such materials and devices. At first, we observe a gradual formation of an I-rich phase, which correlates with an increase in deep defect level concentration. We attribute these deep defects to charged iodide interstitials and associate phase segregation with iodide migration through interstitial positions. Upon further light soaking, the second less I-rich phase forms, while the deep level concentration simultaneously decreases. An empirical model describing the phase segregation mechanism is proposed to rationalize these observations. Further, we point to an important role of grain size in determining the degree and terminal phase of segregation.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk