Structure and optoelectronic properties of PbSe quantum dots /PVA. Does the polymer molecular weight matter?
(2550–2555)Polymers for Advanced Technologies 22 #12 (2011)
Mahmoud of King Abdulaziz University, Saudi Arabia, prepared polyvinyl alcohol (PVA) with different molecular weights (8000, 14,000, and 132,000 g/mol) capped lead selenide (PbSe) quantum dots (QDs).  The particle size of PbSe QDs decreases with the increased PVA molecular weight and/or PVA amount. This may be due to the increase in molecular weight inhibiting further growth of PbSe into the polymer matrix. Thermogravimetric analysis showed that the introduction of PbSe QDs into PVA decreases the crystallinity of the polymer. The optical absorption spectroscopy of prepared nanocomposites showed that the absorption peaks are strongly shifted to the lower wavelength (blue shift) from near infrared region to visible region by increasing the PVA molecular weight. The (I–V) characteristic curves of the PVA/PbSe nanocomposite films under illumination showed a photovoltaic cell-like behavior. The results indicated that as the molecular weight of polymer increases, the conversion efficiency increases.  (RDC 11/25/2011)