Effect of the polymer ordering on the optical spectra and thermoluminescence of polygermane and polysilane films and nanocomposites

Comparative study of optical spectra and thermoluminescence of poly(di-n-hexylgermane) (PDHGe) and poly(di-n-hexylsilane) (PDHS) films and nanocomposites with different degrees of ordering have been carried out in the temperature range 5-200K. The disordering processes, which are essential for PDHGe, lead to the appearance of additional bands in its optical spectra associated with different set of trans- and gauche-conformations of the polymer chain as well as to the broadening of vibrational bands in Raman spectrum. It is shown that polymer chains of confined PDHGe introduced into the nanopores of SBA-15 silica, in contrast to those of PDHS have the gauche-conformation instead of the trans-conformation, as a result of decrease of intermolecular interaction between the polymer chain segments and increase of their mobility. Besides, appearance of discrete levels of the carriers' activation energy in thermoluminescence of both polymers were observed, energies of which coincide with the optical vibration quanta. Disordering processes cause reduction of the number of observed discrete levels of the activation energy for PDHGe.