title: Controlled transition dipole alignment of energy donor and energy acceptor molecules in doped organic crystals, and the effect on intermolecular Förster energy transfer.
abstract: The orientation factor κ(2) ranging from 0 to 4, which depends on the relative orientation of the transition dipoles of the energy donor (D) and the energy acceptor (A) in space, is one of the pivotal factors deciding the efficiency and directionality of resonance energy transfer (RET) in a D-A molecular system. In this work, tetracene (Tc) and pentacene (Pc) are successfully doped in a trans-1,4-distyrylbenzene (DSB) crystalline lattice to form definite D-A mutually perpendicular transition dipole orientations. The cross D-A dipole arrangement results in an extremely small orientation factor, which is about two orders smaller than that in the disordered films. The energy transfer properties from the host (DSB) to the guest (Tc/Pc) were investigated in detail by steady-state as well as time-resolved fluorescence spectroscopy. Our experimental research results show that the small value of κ(2) allows less or partial energy transfer from the host (DSB) to the guest (Tc) in a wide range of guest concentration, with the Förster distance of around 1.5 nm. By controlling the doping concentrations in the Tc and Pc doubly doped DSB crystals, we demonstrate, as an example, for the first time the application of the restricted energy transfer by D-A cross transition dipole arrangement for preparation of a large-size, white-emissive organic crystal with the CIE coordinates of (0.36, 0.37) approaching an ideal white light. In contrast, Tc is also doped in an anthracene crystalline lattice to form head-to-tail D-A transition dipole alignment, which is proved to be highly effective to promote the intermolecular energy transfer. In this doped system, the orientation factor is relatively large and the Förster distance is around 7 nm.
authors: State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou, P R China.
authors: Huan
authors: H
authors: Wang
authors: Bailing
authors: B
authors: Yue
authors: Zengqi
authors: Z
authors: Xie
authors: Bingrong
authors: B
authors: Gao
authors: Yuanxiang
authors: Y
authors: Xu
authors: Linlin
authors: L
authors: Liu
authors: Hongbo
authors: H
authors: Sun
authors: Yuguang
authors: Y
authors: Ma
mesh_terms: D000873:Anthracenes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004735:Energy Transfer; D031541:Fluorescence Resonance Energy Transfer; D009279:Naphthacenes / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*; D000096926:Benzenesulfonamides
chemical_list: D000873:Anthracenes; D009279:Naphthacenes; D013449:Sulfonamides; C007563:1,2-di-(4-sulfamidophenyl)-4-butylpyrazolidine-3,5-dione; D000096926:Benzenesulfonamides; C523499:pentacene; C034020:anthracene; C487736:naphthacene