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The absorption, photoluminescence, and photoluminescence excitation spectra of CdS nanocrystals formed by the Langmuir–Blodgett method are explored. Features of the absorption and photoluminescence excitation spectra defined by optical transitions in the matrix and nanocrystals are identified. The efficiency of electronic excitation transfer from an organic matrix to nanocrystals is studied. It is shown that charge carriers efficiently transfer from the matrix to electron and hole size-quantization levels in nanocrystals and to acceptor defect levels in the band gap of nanocrystals. A large Stokes shift defined by fine exciton structure (bright and dark excitons) is observed. The shift is in the range 140–220 meV for nanocrystals 2.4 and 2.0 nm in radius.

The photoluminescence kinetics in CdS nanocrystals produced by the Langmuir-Blodgett technique is studied at a temperature of 5 K. The photoluminescence kinetics is described by the sum of two exponential functions, with characteristic times of about 30 and 160 ns. It is found that the fast and slow decay times become longer, as the nanocrystal size increases. Analysis of the data shows that the fast decay time is controlled by trion recombination in nanocrystals with defects, whereas the slow decay time is controlled by the annihilation of optically inactive excitons in nanocrystals without defects. It is established that, as the nanocrystal size is decreased, the fraction of imperfect nanocrystals is reduced because of an increase in the energy of defect formation.

Photoluminescence (PL) properties of CdS nanoparticles were studied depending on spacing between the nanoparticles and carbon nanotube (CNT) surface. Using a chemical bath deposition procedure the nanoparticles were grown directly on CNT arrays or arrays covered by a polystyrene layer. The polymer thickness was changed by varying the polystyrene concentration in a solution and the duration of CNT immersing. Transmission electron microscopy and atomic force microscopy were used for estimation of CdS nanoparticle size. An increase in the separation between CdS and CNTs was found to enhance the PL intensity and contribute to the exciton lifetime. PL spectra of CdS nanoparticles grown on a CNT surface and polystyrene layer coating the CNTs.