Photoinduced metastability and degradation of poly[methyl(phenyl)silylene]as seen by thermoluminescence

Photodegradation of pory[methyl(phenyl)silylene] (PMPSi) was studied by tow -temperature thermoluminescence and photoluminescence. It has been found th at this process is nearly reversible at moderate UV exposure; the reverse r eaction could be accelerated thermally. The activation energy of the anneal ing process was determined as 0.65 eV. Different character of the photadegr adation was found under the excitation with 366 nm and 250-280 nm light at room temperature (i.e., within sigma-sigma* and pi-pi *transitions, respect ively), sigma-sigma* excitation leads to the formation of deep charge carri er traps (E-t= 0.45 eV) of photodestructive origin which are associated wit h photoscission of Si bonds in the backbone. The presence of electron accep tor dopants strongly inhibits the trapping ability of these traps.