Luminescent and Optically Detected Magnetic Resonance Studies of CdS/PVA Nanocomposite

Abstract

A series of solid nanocomposites containing CdS nanoparticles in polymeric matrix with varied conditions on the interface particle/polymer was fabricated and studied by photoluminescence (PL) and optically detected magnetic resonance (ODMR) methods. The results revealed interface-related features in both PL and ODMR spectra. The revealed paramagnetic centers are concluded to be involved in the processes of photo-excited carriers relaxation.

Optically detected magnetic resonance study of relaxation/emission processes in the nanoparticle-polymer composite

“…The spectra of both composites are complex, with three strongly overlapping components. In the case of CdS/PVA, these are the LK1, LK2, and LK3 signals already reported by us earlier [34]. All of them are positive.…”

“…Keeping in mind that both types of nanocomposites demonstrate similar "green" PL bands, though of dramatically different intensity (Fig. 1b), most probably the corresponding light-emitting centers are not related to either oxygen or nitrogen (note that "green" band in CdS/PVA was ascribed to surface in [34]). On the contrary, the emission in red and near-IR ranges, which dominates in CdS/PVA, may involve oxygen-containing interfacial centers.…”

“…According to our recent PL study of the CdS/PVA system, its emission spectrum contains four overlapping components: the blue band corresponding to residual emission from the polymeric matrix and three NP-related bands, one in the green region and two others in red and near IR ranges [34]. Even though no contribution of the PEI matrix to the PL spectrum of the CdS/PEI nanocomposite was established [7,8,30], the wide structureless PL lineshape (Fig.…”

“…In Ref. [34], it was suggested that at least two PL bands of CdS/PVA composite originate from the surface states. Therefore, the differences between CdS/PVA and CdS/PEI spectra should be analyzed with account of different matrices.…”

Electronic Properties of Surface Vacancies in CdS Nanocrystals

“…Дослідженню фотолюмінесцентних властивостей та встановленню механізмів випромінювальної рекомбінації нанокристалів CdS присвячена ціла серія робіт [14][15][16][17][18][19]. Проте, ще багато факторів є невизначеними, зокрема нез'ясованою залишається природа центрів випромінювальної рекомбінації в НК CdS.…”