Triplet photophysical properties of poly(2-vinylnaphthalene) and poly(N-vinylcarbazole) solid films in a low-temperature regime

Journal Article · Thu Jun 15 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100349a023· OSTI ID:6752263

Chakraborty, D K; Burkhart, R D ^[1]

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1. Univ. of Nevada, Reno (USA)

The delayed fluorescence intensity from solid films of poly(2-vinylnaphthalene) (P2VN) and poly(N-vinylcarbazole) (PVCA) both yield maxima below 77 K when plotted as a function of temperature. For PVCA, earlier work had already established the existence of one maximum at 200 K along with a minimum at 145 K. Thus, the new maximum observed here near 40 K is the third extremum found for this polymer verifying earlier predictions of its existence. For P2VN a maximum in the delayed fluorescence-temperature profile is found near 55 K but no others are observed up to ambient temperature. The major source of delayed fluorescence intensity in both polymers is thought to arise from triplet-triplet hetero annihilations involving a mobile triplet exciton, T{sub m}, and a shallow-trapped one, T{sub s}. The increase in DF intensity from the lowest temperature up to the low-temperature maximum is due to an increasing rate of T{sub m} mobility. The maximum occurs at a temperature such that the rate of thermally induced detrapping of T{sub s} approaches that of competing processes for its relaxation to the ground state. A similar mechanism is proposed for PVCA. This mechanism is consistent with the observation that the low-temperature maxima disappear at long times after the excitation pulse and that the temperature corresponding to the maximum increases as the delay time decreases.

• OSTI ID: 6752263
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:12; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AROMATICS
CARBONYLS
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
FILMS
HYDROXY COMPOUNDS
INFORMATION
LOW TEMPERATURE
MEASURING INSTRUMENTS
MEASURING METHODS
NAPHTHOLS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PHENOLS
PHOTOCONDUCTORS
PHYSICAL PROPERTIES
POLYMERS
THIN FILMS