Organic semiconductor materials such as planar conjugated small molecules are of great interest to the photovoltaic community. In thin films, the exciton and charge carrier dynamics, which are crucial to photovoltaic device operation, depend in a non-trivial way on the organic molecular structure and on the molecular organization in the solid state. Recently, the exciton diffusion has been found to strongly depend on the crystalline order of the organic thin films. This work presents the study of the exciton lifetime in an innovative class of molecular semiconductors able to present different crystalline order. This family of molecules has a “dumbbell-shaped” structure based on triazatruxene units that act as a π-stacking platform. Such molecules with different side-chains have been found to self-assemble into various crystalline and liquid crystalline phases. We have studied the steady-state photoluminescence and the exciton lifetime for several triazatruxene-based derivatives with different side-chains, in solution and in thin films for different solid state phases. In solution, the fluorescence lifetime corresponds to the reference value that can be obtained without intermolecular interaction. In thin films, we measured the exciton lifetime for different molecular structures in order to correlate the exciton dynamics with the molecular stacking. The results reveal a significant increase in the exciton lifetime with the enhancement of the structural order.
Long-lived room temperature ‘phosphorescence’ from organic molecular crystals has attracted great attention owing to potential applications in organic electronics, information storage, and biotechnologies. The features of the persistent luminescence strongly depend on the electronic properties of the individual molecules, and on their molecular packing in the crystal lattice. Here, a new strategy is developed by rationally designing phosphors incorporating and combining for the first time a bridge for sigma-conjugation and a moiety for H-bond-directed supramolecular self-assembly. The molecular crystals exhibit room temperature ‘phosphorescence’ quantum yields that reach up to 20% and lifetimes up to 520 ms. This study provides a promising strategy for the development of molecular crystals exhibiting efficient long-lived room temperature persistent luminescence.
Long-lived room temperature phosphorescence from organic molecular crystals has attracted great attention owing to potential applications in organic electronics, information storage, and biotechnologies. The features of the persistent luminescence strongly depend on the electronic properties of the individual molecules, and on their molecular packing in the crystal lattice. Here, a new strategy is developed by rationally designing phosphors incorporating and combining for the first time a bridge for sigma-conjugation and a moiety for H-bond-directed supramolecular self-assembly. The molecular crystals exhibit room temperature phosphorescence quantum yields that reach up to 20% and lifetimes up to 520 ms. This study provides a promising strategy for the development of molecular crystals exhibiting efficient long-lived room temperature phosphorescence.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.