The nature of recombination centres in silver- and chlorine-doped CdS phosphors

The Role of Spatial Potential Fluctuations in the Shape of the PL Bands of Multinary Semiconductor Compounds

“…The Ñuctuations of defect potentials cause widening of the defect levels within the forbidden gap of CIGS and so-called band tails are formed. Spatial potential Ñuctuations are quite common in highly doped and compensated semiconductors [4,5], for which the theory describing the electrical and optical properties was developed by Shklovskii and Efros [6], and by Levanyuk and Osipov [7]. It was shown that the edge emission in highly compensated semiconductors essentially includes two typical emission bands : the band to tail (BT) and the band to band (BB) bands, shown schematically in Fig.…”

Excitonic pathway to photoinduced magnetism in colloidal nanocrystals with nonmagnetic dopants

“…For small, wide-bandgap CdSe NCs (energy gap, E g > 2.1 eV), the Mn d states behave as radiative recombination centres for band-edge excitons, resulting in the typical Mn 2+ luminescence at ~2.1 eV sensitized by the host particle 9 , whereas for larger NCs (E g < 2.1 eV), the unpaired electronic spins of the Mn ions interact with photogenerated 17 and electrically injected 18 excitons to form magnetic polarons. Conversely, Cu and Ag ions introduce a single intragap deep acceptor level close to the host valence band (VB) [19][20][21][22] , which radiatively captures a conduction band (CB) electron 10,11,23,24 , making the dopant-related emission subject to quantum confinement and heterostructuring 23 . Being aliovalent with respect to cations in ii-vi and iii-v semiconductors, their insertion changes the overall charge within the host compound, resulting in p-or n-type doping depending on their coordination state 11,12,[23][24][25][26] .…”

“…As a result, Ag cations assume the + 1 oxidation state almost exclusively, whereas the stable + 2 configuration is found in rare compounds where Ag 2+ ions are protected against reduction by suitable ligands 28,32 . Consistently, in bulk metal chalcogenides, Ag atoms are inserted as nonmagnetic + 1 impurities 33 with electronic configuration [Kr]4d 10 , often coupled to a compensating defect ensuring charge neutrality 19,34 . Having a full d shell, luminescence in Ag-doped systems requires transfer of the photoexcited hole from the host VB to the Ag + site, which then behaves as a radiative acceptor centre for a CB electron 24,29,34,35 .…”

Hollow micro/nanostructured materials prepared by ion exchange synthesis and their potential applications

“…Columnar and tubular films of Ag 2 S, Cu 2 S, Bi 2 S 3 , or Sb 2 S 3 were prepared from columnar ZnO films. [70][71][72][73][74] With respect to anion exchange, Wang and co-workers reported the transformation of columnar ZnO into tubular ZnS by exposure to H 2 S gas. 75 The conversion of ZnO into ZnS nanotubes occurred in solution and was formed by a direct reaction of H 2 S with the surface layer of ZnO in the presence of water.…”