Enhancement of the photoluminescence in CdSe quantum dot–polyvinyl alcohol composite by light irradiation

• Published in: Applied surface science Vol. 281; pp. 118 - 122
• Main Authors: Borkovska, L., Korsunska, N., Stara, T., Gudymenko, O., Venger, Ye, Stroyuk, O., Raevska, O., Kryshtab, T.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15.09.2013; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Photoluminescence; Physics; Polyvinyl alcohol; Quantum dots; X-ray diffraction; X-ray diffraction; Polyvinyl alcohol; Quantum dots; Photoluminescence; Inorganic compounds; Composite materials; Semiconductor materials; Physical radiation effects; Transition element compounds; XRD; Cadmium selenides
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.12.146

► The effect of photo-induced enhancement of deep trap photoluminescence (PL) of quantum dots (QDs) is found. ► The effect is observed in the CdSe QDs embedded in polyvinyl alcohol (PVA) film. ► The effect is caused by the increase of the activation energy of the PL thermal quenching. ► The effect is ascribed to change of QD surface defect passivation caused by photochemical transformations at the QD/PVA interface. The effect of photo-induced enhancement (more than a tenfold) of room temperature deep-trap photoluminescence (PL) in CdSe quantum dots (QDs) embedded in polyvinyl alcohol (PVA) film has been found and investigated by the PL and X-ray diffraction methods. The effect is observed under illumination of the QD/PVA composite with LED's light of 409 or 470nm at elevated temperatures and is shown to be caused by an increase of the activation energy of thermal quenching of defect-related PL. It is shown that thermal annealing of the composite by itself stimulates polymer crystallization and produces a small increase in the intensity of both the band-edge and defect-related PL bands of CdSe QDs. It is found that the effect of illumination decreases when the annealing temperature increases from 90°C to 120°C because thermal annealing at 120°C per se results in strong enhancement of room temperature deep-trap PL. The effect of photo-induced enhancement of defect-related PL is found to be irreversible and is assumed to be related to the change of QD surface defect passivation or surface defect rearrangement. This is ascribed to partial destruction of PVA matrix as a result of interaction of QD/PVA interface with photocarriers generated in the QDs due to LED's light absorption.