✦ LIBER ✦

The origin of delayed fluorescence in charge-transfer crystals: pyromellitic dianhydride-phenanthrene crystal

✍ Scribed by B. Kozankiewicz

Publisher: Elsevier Science
Year: 1987
Tongue: English
Weight: 382 KB
Volume: 134
Category: Article
ISSN: 0009-2614
DOI: 10.1016/0009-2614(87)87145-2

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✦ Synopsis

The temperature dependence of emission spectra and their decay parameters for pyromellitic dianhydride-phenanthrene chargetransfer crystals have been investigated between 1.7 and 300 K. It has been established that the delayed fluorescence originates from triplet-triplet annihilation at temperatures between 30 and 60 K (activation energy 29Ok 20 cm-') and from thermal activation of triplet excitons to the singlet excitonic band for temperatures higher than 60 K (activation energy 600 f 30 cm-'). This mechanism may be considered as typical for charge-transfer crystals characterized by intermediate (SO-SO%) charge-transfer character of triplet excitons.

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