The effect of bio-conjugation on aging of the photoluminescence in CdSeTe–ZnS core–shell quantum dots

► We study the aging of luminescence in CdSeTe–ZnS quantum dots (QDs) dried on Si wafer. ► Upon aging the QD luminescence band blue shifts, broadens and decreases in intensity. ► The aging is ascribed to QD oxidation and is more pronounced in bio-conjugated QDs. ► The mechanism of the influence of bio-conjugation on QD oxidation is proposed. The aging of the photoluminescence (PL) in bio-conjugated and non-conjugated CdSeTe–ZnS core–shell quantum dots (QDs) is studied by the micro-PL, micro-Raman and X-ray diffraction (XRD) in the samples of buffered QD solution dried on a crystalline Si wafer and stored in the atmospheric ambience for about 2years. The aging of the PL consists in a “blue” spectral shift of the PL band, an increase in PL band half-width and the decrease in the PL intensity. These changes are more pronounced in the conjugated QD samples. The XRD analysis of the aged samples revealed that the QD core diameter is reduced by ∼1.5nm in the conjugated QDs as compared to the non-conjugated ones. The possible mechanism of PL spectrum aging is the oxidation that decreases the QD core dimension. It is concluded that the bio-conjugation promotes QD oxidation and the mechanism of the effect is proposed.