Photoluminescence from silicon-chain cluster in poly(dimethylsilane) evaporated film

Photoluminescence (PL) and excitation (EX) spectra in epitaxially grown poly(dimethylsilane) (PDMS) films prepared by evaporation have been measured. The epitaxial films are prepared onto mechanically oriented poly(tetrafluoroethylene) (PTFE) layer or onto cleaved surface of alkali halide crystals. The EX peak is located in the lower photon energy tail of the broad absorption (ABS) band; this is explained in terms of the occurrence of energy transfer from short delocalized regions to the longest delocalized regions in silicon main chain and the extremely poor transfer probability. The epitaxially grown films show higher photoluminescence intensity possibly because the existence of an increased number of delocalized regions.