Photoacoustic characterization of optical and thermal properties of CdSe quantum dots

We report on the optical absorption properties of as prepared CdSe quantum dots (QDs) measured by the photoacoustic (PA) method. CdSe QDs were fabricated by the chemical solution deposition (CD) technique. With increasing growing time, the redshift of the PA spectra can be clearly observed and optical absorption in the visible region due to CdSe Q-dots is demonstrated. The average diameters of the CdSe QDs for each growth time interval is estimated using the effective mass approximation giving diameters ranging from 2.6 nm to 3.4 nm. These values are comparable to those obtained by scanning tunnelling microscope (STM). Thus, PA spectroscopy is useful to obtain the QDs sizes as grown and with no further preparation. In addition, PA measurements provide also the thermal diffusivity of samples of different sizes which in this case show an increase by at least an order of magnitude than the bulk value.