title: Rational Design of Charge-Transfer Interactions in Halogen-Bonded Co-crystals toward Versatile Solid-State Optoelectronics.
abstract: Charge-transfer (CT) interactions between donor (D) and acceptor (A) groups, as well as CT exciton dynamics, play important roles in optoelectronic devices, such as organic solar cells, photodetectors, and light-emitting sources, which are not yet well understood. In this contribution, the self-assembly behavior, molecular stacking structure, CT interactions, density functional theory (DFT) calculations, and corresponding physicochemical properties of two similar halogen-bonded co-crystals are comprehensively investigated and compared, to construct an "assembly-structure-CT-property" relationship. Bpe-IFB wire-like crystals (where Bpe = 1,2-bis(4-pyridyl)ethylene and IFB = 1,3,5-trifluoro-2,4,6-triiodobenzene), packed in a segregated stacking form with CT ground and excited states, are measured to be quasi-one-dimensional (1D) semiconductors and show strong violet-blue photoluminescence (PL) from the lowest CT1 excitons (ΦPL = 26.1%), which can be confined and propagate oppositely along the 1D axial direction. In comparison, Bpe-F4DIB block-like crystals (F4DIB = 1,4-diiodotetrafluorobenzene), packed in a mixed stacking form without CT interactions, are determined to be insulators and exhibit unique white light emission and two-dimensional optical waveguide property. Surprisingly, it seems that the intrinsic spectroscopic states of Bpe and F4DIB do not change after co-crystallization, which is also confirmed by theoretical calculations, thus offering a new design principle for white light emitting materials. More importantly, we show that the CT interactions in co-crystals are related to their molecular packing and can be triggered or suppressed by crystal engineering, which eventually leads to distinct optoelectronic properties. These results help us to rationally control the CT interactions in organic D-A systems by tuning the molecular stacking, toward the development of a fantastic "optoelectronic world".
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|University of Chinese Academy of Sciences , Beijing 100049, P. R. China.
authors.forename: Weigang
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Renhui
authors.initials: R
authors.lastname: Zheng
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zhen
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|University of Chinese Academy of Sciences , Beijing 100049, P. R. China.
authors.forename: Zhenyi
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Huanli
authors.initials: H
authors.lastname: Dong
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Hongbing
authors.initials: H
authors.lastname: Fu
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|Collaborative Innovation Center of Chemical Science and Engineering and School of Science, Tianjin University , Tianjin 300072, China.
authors.forename: Wenping
authors.initials: W
authors.lastname: Hu
mesh_terms: D003460:Crystallization; D004581:Electronics; D004980:Ethane / Q000031:analogs & derivatives / Q000737:chemistry; D005464:Fluorobenzenes / Q000737:chemistry; D006219:Halogens / Q000737:chemistry*; D007462:Iodobenzenes / Q000737:chemistry; D049449:Luminescence; D010316:Particle Size; D011725:Pyridines / Q000737:chemistry; D011789:Quantum Theory; D012666:Semiconductors
chemical_list: C572924:1,2-bis(4-pyridyl)ethene; D005464:Fluorobenzenes; D006219:Halogens; D007462:Iodobenzenes; D011725:Pyridines; D004980:Ethane