Electronic excitations of poly(methylphenylsilane) films
- Sandia National Laboratories, Albuquerque, New Mexico 87185 (USA)
- 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), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:15; ISSN 0163-1829; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoinduced charge transfer and charge carrier generation in polysilane films containing C[sub 60] molecules
Photoinduced refractive index change and absorption bleaching in poly(methylphenylsilane) under varied atmospheres.
Related Subjects
360603* -- Materials-- Properties
ABSORPTION
ALKYL RADICALS
AROMATICS
CHAINS
CHARGE CARRIERS
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRO-OPTICAL EFFECTS
ENERGY ABSORPTION
ENERGY GAP
ENERGY LEVELS
ENERGY SPECTRA
EXCITED STATES
EXCITONS
EXPERIMENTAL DATA
FILMS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
LOW TEMPERATURE
MEDIUM TEMPERATURE
METHYL RADICALS
MULTI-PHOTON PROCESSES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHOTOCONDUCTIVITY
PHYSICAL PROPERTIES
POLYPHENYLS
QUASI PARTICLES
RADICALS
SILANES
SILICON COMPOUNDS
SPECTRA
THIN FILMS
ULTRALOW TEMPERATURE
VAN DER WAALS FORCES