Electronic structure mapping of branching states in poly[methyl(phenyl)silane] upon exposure to UV radiation

The origin of white photoluminescence in polysilanes has long been disputed, and this emission is closely connected with information recording in nanotechnologies. We elucidated UV degradation of an archetypal model polymer poly[methyl(phenyl)silane] by using a new method for electronic structure ma...

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Bibliographic Details
Published in:	Journal of the Korean Physical Society Vol. 68; no. 4; pp. 563 - 568
Main Authors:	Schauer, František, Tkáč, Lukáš, Ožvoldová, Miroslava, Nadáždy, Vojtech, Gmucová, Katarána, Végsö, Karol, Tkáčová, Miroslava, Chlpík, Juraj
Format:	Journal Article
Language:	English
Published:	Seoul The Korean Physical Society 01-02-2016 한국물리학회
Subjects:	Mathematical and Computational Physics Particle and Nuclear Physics Physics Physics and Astronomy Theoretical 물리학 Information recording Energy-resolved electrochemical impedance spectroscopy Branching states Density of electronic states Organic semiconductors Polysilane degradation White photoluminescence Nanomasks production
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Summary:	The origin of white photoluminescence in polysilanes has long been disputed, and this emission is closely connected with information recording in nanotechnologies. We elucidated UV degradation of an archetypal model polymer poly[methyl(phenyl)silane] by using a new method for electronic structure mapping of organic semiconductors, energy-resolved electrochemical impedance spectroscopy (ER-EIS) and photoluminescence spectroscopy. UV exposure at 345 nm resulted in two defect bands above the highest occupied molecular orbital (HOMO) in the energy region from −5.5 eV to −3.5 eV with respect to the zero vacuum energy level. The respective density of states was 10 16 − 10 17 cm −3 eV −1 , and the total integrated concentration was 0 − 10 17 cm −3 . The photoluminescence in the long-wavelength region gave wide bands with photon energies from 2.2 eV to 3.2 eV (corresponding to wavelengths from 600 nm to 390 nm). The observed bands were interpreted by assuming the formation of energetically distributed Si branching radiative states, whose distribution in the HOMO − lowest unoccupied molecular orbital (LUMO) gap was observed by using ER-EIS. The quantum efficiency of defect state formation increased from Φ(x) 345 nm = 0.0045 to Φ(x) 290 nm = 0.053. The obtained results may contribute to the production of effective polysilane nanomasks and to information recording.
Bibliography:	G704-000411.2016.68.4.001
ISSN:	0374-4884 1976-8524
DOI:	10.3938/jkps.68.563