Influence of the molecular geometry on the photoexcitations of highly emissive organic semiconductors
學年 88
學期 1
發表日期 1999-12-17
作品名稱 Influence of the molecular geometry on the photoexcitations of highly emissive organic semiconductors
作品名稱（其他語言）
著者 Yang, Shu-chun; Graupner, W.; Guha, S.
作品所屬單位 淡江大學物理學系
出版者 SPIE-The international society for optical engineering
會議名稱 Proceedings of the SPIE v.3797, Organic light-emitting materials and devices III
會議地點 Bellingham, WA, USA
摘要 Para-phenylene type molecules are efficient photoluminescence emitters in the ultraviolet-blue-green spectral range. They are used in light emitting diodes (LEDs) and photopumped lasers. Photoexcited para-phenylene type molecules give rise to strong emission from singlet excitons, bleaching of the singlet exciton absorption, induced absorption from triplet excitons and induced absorption from polarons. Since the latter two processes represent absorption of the emitted light of singlet excitons, the presence of polarons and triplet excitons might be a fundamental problem for laser diodes made from para-phenylene type molecules. In our experiments we modify the molecular geometry by the application of hydrostatic pressures up to 80 kbar in a temperature range of 10 to 300 K. In particular we show how triplet and polaron states, which are present in LEDs under operation, react to the induced geometric changes. The spectra of ground state absorption, excited state emission, bleaching of the singlet exciton absorption, induced absorption from triplet excitons and induced absorption from polarons are significantly broadened and shifted in energy. In order to explain the observed behavior we have performed three-dimensional bandstructure calculations within density functional theory for the planar poly(para-phenylene). By varying the intermolecular distances and the length of the polymer repeat unit pressure effects can be simulated.
關鍵字
語言 en
收錄於
會議性質 國際
校內研討會地點
研討會時間 19991217~19991217
通訊作者
國別 USA
公開徵稿 Y
出版型式 紙本
出處 Proceedings of the SPIE v.3797, Organic light-emitting materials and devices III,pp.26-37
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