Premium
Photoconduction in Polydiacetylene Multilayer Structures and Single Crystals. Evidence for Band‐to‐Band Excitation
Author(s) -
Lochner K.,
Bässler H.,
Tieke B.,
Wegner G.
Publication year - 1978
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220880232
Subject(s) - exciton , excitation , valence (chemistry) , materials science , perpendicular , direct and indirect band gaps , band gap , condensed matter physics , quasi fermi level , conduction band , spectral line , molecular physics , atomic physics , chemistry , physics , electron , geometry , mathematics , organic chemistry , quantum mechanics , astronomy
Steady state photoconduction action spectra for polydiacetylene multilayer structures and single crystals (TCDU) are reported. Interpretation is given in terms of a valence‐to‐conduction band transition which is buried under the vibronic sidebands of the dominant exciton transition. The associated absorption coefficient follows a (α b ħω) ˜ (ħω − E g ) 2 law which indicates either an indirect transition or a direct transition between non‐parabolic bands. The general validity of this relationship is supported by literature data for PTS, DCHD, and polyethylene. Gap energies are (2.5 ± 0.1) eV and (2.6 ± 0.1) eV for two different multilayer forms, (2.6 ± 0.1) eV for TCDU, (2.1 ± 0.1) eV for PTS, and (2.30 ± 0.05) eV for DCHD. The transition is three‐dimensional indicating finite valence and conduction band dispersion perpendicular to the polymer chain direction.