Photoinduced Metastability and Degradation of Poly[Methyl (Phenyl)Silylene] as seen by Thermoluminescence

Abstract

Photodegradation of poly[methyl(phenyl)silylene] (PMPSi) was studied by low-temperature thermoluminescence and photoluminescence. It has been found that this process is nearly reversible at moderate UV exposure; the reverse reaction could be accelerated thermally. The activation energy of the annealing process was determined as 0.65 eV. Different character of the photodegradation was found under the excitation with 366 nm and 250–280 nm light at room temperature (i.e., within [sgrave]-[sgrave]* and π-π* transitions, respectively), σ-σ* excitation leads to the formation of deep charge carrier traps (E_t = 0.45 eV) of photodestructive origin which are associated with photoscission of Si bonds in the backbone. The presence of electron acceptor dopants strongly inhibits the trapping ability of these traps.

Key Words:

• photodegradation
• poly[methyl(phenyl)silylene]
• thermally stimulated luminescence
• photoluminescence
• Si bonds scission
• charge carrier traps