Electronic excitations of poly(methylphenylsilane) films

Journal Article · Wed May 15 00:00:00 EDT 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.12530· OSTI ID:5487638

Kepler, R G ^[1]; Soos, Z G ^[2]

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1. Sandia National Laboratories, Albuquerque, New Mexico 87185 (USA)
2. Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (USA)

We report electroabsorption (EA), two-photon absorption (TPA), and the spectrum for charge-carrier generation in thin films of poly(methylphenylsilane) (PMPS). The one-photon absorption to a singlet exciton, which begins at {ital E}{sub {ital g}}=3.5 eV, appears in EA and indicates a polarizability change of 1.8{times}10{sup {minus}22} cm{sup 3}. The onset around 4.6 eV of direct generation of charge carriers by photons defines the interband gap {ital E}{sub {ital b}} and correlates with an EA feature at 4.65 eV that we associate with charge transfer between polymer segments. The TPA around 4.4 eV is to the second {sup 1}{ital A}{sub {ital g}} state and gives the alternation gap {ital E}{sub {ital a}}, while the broad TPA above 5 eV is assigned to an even-parity state derived from exciting two electrons across {ital E}{sub {ital g}}. A Pariser-Parr-Pople model for {sigma} conjugation in polysilanes accounts for {ital E}{sub {ital g}}, for polarizability changes, for TPA, and for the singlet-triplet gap {ital E}{sub {ital t}} in terms of correlated states. We contrast the spectra of amorphous PMPS with films of poly(di-{ital n}-hexylsilane), whose side groups are ordered at low temperature, and compare EA spectra in polysilanes with EA in crystalline organic solids and wideband semiconductors.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5487638
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 43:15; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
METHYL RADICALS
EXCITED STATES
POLYPHENYLS
SILANES
CHAINS
CHARGE CARRIERS
ELECTRO-OPTICAL EFFECTS
ENERGY ABSORPTION
ENERGY GAP
ENERGY SPECTRA
EXCITONS
EXPERIMENTAL DATA
LOW TEMPERATURE
MEDIUM TEMPERATURE
MULTI-PHOTON PROCESSES
PHOTOCONDUCTIVITY
THIN FILMS
ULTRALOW TEMPERATURE
VAN DER WAALS FORCES
ABSORPTION
ALKYL RADICALS
AROMATICS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY LEVELS
FILMS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHYSICAL PROPERTIES
QUASI PARTICLES
RADICALS
SILICON COMPOUNDS
SPECTRA
360603* - Materials- Properties