Spin polarization effects in the photoluminescence of polythiophene

Technical Report · Fri Jul 01 00:00:00 EDT 1988

OSTI ID:6399201

Hess, B C

Photoluminescence (PL), optically detected magnetic resonance (ODMR), and nonresonant magnetic field effects (NFE) have been studied in polythiophene (PT) and poly(3-alkylthiophene) (P3AT). The PT samples studied were chemically coupled PT (c-PT) and electrochemically coupled PT (e-PT); the P3AT samples were poly(3-hexylthiophene) (HPT) and a copolymer of 3-benzylthiophene and 3-hexylthiophene (BHPT). The PL spectra of PT and P3AT exhibit a broad band centered between 1.6--1.9 eV, a narrow peak at 1.8--1.95 eV, and 0.18 eV phonon replicas of the narrow peak. The PL spectrum of e-PT is similar to the published spectra, while the PL of c-PT is dominated by a broad band centered near 1.6--1.7 eV, in contrast to previously published results. HPT and BHPT show almost identical PL spectra. In all samples, the integrated PL intensity is nearly temperature dependent. ODMR was measured at X-band from 5 to 300K. Strong PL-enhancing signals (..delta..L/L approx. = 2 x 10/sup -3/ at low temperatures) were detected at g = 2.003. The strength of the signal and its temperature dependence suggest that the ODMR probes unthermalized spins. In c-PT, the ODMR originates from a broad structureless PL band which is devoid of the phonon sidebands and is centered near 1.65 eV. This band is near the energy expected for photons released in the recombination of photogenerated positive and negative polarons. The ODMR in each sample is composed of two components separated by ..delta..g approx. = 6 x 10/sup -4/. Although these two components are tentatively assigned to recombining positive and negative polarons, the possibility of two distinct long lived recombination mechanisms cannot be excluded. 103 refs., 39 figs.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6399201
• Report Number(s): IS-T-1375; ON: DE89007633
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
DATA
ENERGY LEVELS
EXPERIMENTAL DATA
HAMILTONIANS
INFORMATION
LUMINESCENCE
MAGNETIC FIELDS
MAGNETIC RESONANCE
MATHEMATICAL OPERATORS
NUMERICAL DATA
ORIENTATION
PHOTOLUMINESCENCE
POLYMERS
QUANTUM OPERATORS
RESONANCE
SPIN ORIENTATION