Luminescence

Abstract

This chapter is devoted to the luminescence of inorganic compounds. Luminescence characteristics are strongly host‐dependent. This is illustrated by various examples of the influence of covalency, crystal field, phonon energies, and structural features. The chapter is organized as follows. Section 2 describes the fundamentals of luminescence: probability of electronic transitions, shape of emission bands, quantum efficiency, energy transfer, and factors governing the position of the emitting level (nephelauxetic effect and crystal field splitting). Section 3 reviews the main families of luminescent ions: transition metal ions, lanthanide ions, and s 2 ions. The various types of electronic transitions responsible for the luminescence of transition and lanthanide ions are presented: nd → nd, (n + 1)s → nd, and charge transfer (CT) transitions for the former, 4f → 4f, 5d → 4f, and CT transitions for the latter. Data are given on the luminescence wavelength range, excited‐state lifetimes, thermal stability, and concentration quenching. Section 4 deals with donor‐acceptor transitions in ZnS. Section 5 presents the luminescence mechanisms for excitation through the host lattice. Vacuum ultraviolet (VUV), electron beam, X‐ray, and γ‐ray excitation are considered. The most efficient luminescent materials are given for the various types of excitation. Section 6 deals with electroluminescent materials.

The Chemistry of Cadmium–Thiocarboxylate Derivatives: Synthesis, Structural Features, and Application As Single Source Precursors for Ternary Sulfides

“…The insoluble material was filtered off, and on standing, yellowcolored crystals were obtained in a few days. Yield (based on CdCl Synthesis of [PPh 3 Cd(μ-SCOth)SCOth] 2 3 CH 2 Cl 2 (5). To a stirred solution of sodium thiophene-2-thiocarboxylate (0.210 g, 1.27 mmol) in 5 mL of methanol was added CdCl 2 3 2.5H 2 O (0.145 g, 0.63 mmol), followed by a CH 2 Cl 2 solution of PPh 3 (0.166 g, 0.63 mmol).…”

“…A CdS/Cu 2 S solar cell was one of the first efficient cells known . Furthermore, CdS luminesces under electron beam excitation when doped with Cu + and Al 3+ and is used as a phosphor …”

“…4 Furthermore, CdS luminesces under electron beam excitation when doped with Cu + and Al 3+ and is used as a phosphor. 5 Though a wide variety of methods have been developed to synthesize these materials, 6 the conventional solid state reaction and homogeneous precipitation methods suffer from difficulties like high temperature requirements, long reaction times, the formation of impure products, mixed phases, etc. 7 An attractive method is the single molecular source approach, where the organic fragments present in the metal complexes of sulfur-containing ligands are removed and metal sulfides are reassembled at relatively low temperatures under mild conditions.…”