Slabé vazby a přerušené vazby vytvořené UV v polysilanech

Abstract

studie fotoluminiscence a UV degradace polysilanů, zejména s ohledem na slabé a přerušené vazby

The susceptibility of aryl-substituted polysilylanes to photodegradation by UV radiation is examined on the prototypical organosilicon polymers, poly[methyl(phenyl)silylene] (PMPSi) and poly[(biphenyl-4-yl)methylsilylene] (PBMSi). The main purpose of this work is to study photoluminescence (PL) after UV major degradation for two different degradation wavelengths 266 and 355 nm, predominantly in long wave range 400-600 nm, studying the disorder, dangling bonds (DB) and weak bonds (WB) created by the degradation process. We claim that the PL of the 500-600 nm band is related to the existence of WB on Si chain. Increase of the normalized PL 520-540 nm band after UV degradation can be then evaluated as the increase of the density of states (DOS) of WB. The efficiency of the WB creation in PMPSi is greater for 266 nm irradiation, supporting the notion of the suppressed exciton transport compared to the less energetical photon of 355 nm, where the WB creation is lowered due to the exciton migration to longer segments and/or already existing defects. For PBMSi the WB creation kinetics for 355 nm degradation is similar to that of PMPSi. The 266 nm degradation results then support the model calculations of DB and WB reconstruction in more rigid Si skeleton. (c) 2006 Elsevier B.V. All rights reserved.