The synthesis of the first mesogenic donor‐acceptor polyoxometalate (POM)‐based hybrid is herein described. The structural and electronic properties of the hybrid compound were evaluated through ...combination of small‐ and wide‐angle X‐ray scattering, optical microscopy, electrochemistry and photoluminescence. In the solid state, the compound behaves as a birefringent solid, displaying a lamellar organization in which double‐layers of POMs and bis(thiophene)thienothiophene organic donors alternate regularly. Noticeably, the sub‐unit organizations in the composite are similar to that observed for the individual POM and organic donor precursors. Photophysical studies show that in the hybrid, the fluorescence of the organic donor unit is considerably quenched both in solution and in the solid state, which is attributed to occurrence of intramolecular charge‐separated state.
The synthesis of the first mesogenic donor‐acceptor polyoxometalate (POM)‐based hybrid is presented. In the solid state, the compound displays a lamellar organization in which the sub‐unit organizations are similar to that observed for the individual POM and organic donor precursors. The fluorescence of the donor is considerably quenched both in solution and in the solid state, which is attributed to the occurrence of charge transfer.
Exciton‐polaritons, in which the electronic state of an excited organic molecule and a photonic state are strongly coupled, can form a Bose–Einstein condensate (BEC) at room temperature. However, so ...far, the reported thresholds of organic polariton BECs under optical excitation are as high as Pth = 11–500 μJ cm–2. One route toward lowering the condensation threshold is to increase the Rabi energy by aligning the molecular transition dipole moments. In this report, it is demonstrated that control of the orientation of a perylene‐based discotic dye, which is able to self‐organize in mesogenic columnar structures, can significantly enhance exciton–photon interaction and polariton relaxation rate in optical cavities. These results show the importance of the molecular orientation for strong light–matter interactions and provide a promising strategy toward the realization of an organic low threshold polariton BEC system and electrically driven organic polariton BEC.
This work demonstrates for the first time experimentally, that the orientation of the transition dipole moments is one of the key factors for the accelerating polariton relaxation. These outcomes show that the in‐plane orientation of dipole moments is a promising strategy for lowering the Bose–Einstein condensate (BEC) threshold mainly related to the polariton relaxation rate.
Gold nanorods functionalized with triphenylene‐based discotic liquid crystal (LC) motifs show striking self‐assembly behavior both on transmission electron microscopy (TEM) grids as well as in the ...bulk enforced by the π–π‐stacking of triphenylene groups of adjacent nanorods. TEM images confirm that these discotic LC nanorods form ribbons of parallel‐stacked nanorods several hundred nanometer long. The pursued silane conjugation approach to decorate the nanorods allows for the preparation of dispersions of the nanorods in the hexagonal columnar phases of parent discotic LCs, where the nanorods can be macroscopically aligned with almost 80% efficiency by a simple shearing protocol. Doping the parent host materials with about 1% by weight of the discotic LC‐capped nanorods also reduces the lattice parameter and the intracolumnar packing, which gives rise to enhanced charge carrier mobility in these hosts as determined by time‐of‐flight measurements.
Tiny amount, big effect: Gold nanorods capped with discotic liquid crystal motifs self‐assemble into nanorod ribbons several hundred nanometer long, and can be macroscopically aligned in the parent discotic liquid crystal. At only 1% by weight, these nanorods affect the packing of the host phase leading to an increase in charge carrier mobility in the columnar phase.
Single-crystals of unsubstituted 1Benzothieno3,2-b1-benzothiophene (BTBT) were prepared by physical vapor transport deposition (VTP). The packing structure and morphology of the crystals were studied ...by X-ray diffraction (XRD), polarized optical microscopy (POM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The charge transport properties of BTBT single-crystals were also investigated via bottom contact/bottom gate (BC/BG) organic field-effect transistors (OFETs) on both SiO2 and n-octadecyltrichlorosilane (OTS) treated surfaces. A maximum hole mobility value of 0.032 cm2V−1s−1 was measured on the OTS substrate. In addition, single-crystal OFETs with ion gel top gate (TG) configuration were also investigated for low voltage operation. This work represents the first investigation of charge carrier mobility of a simple BTBT in transistor configuration and highlights the essential role of the BTBT substitution in charge transport properties.
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•Single crystals of unsubstituted 1Benzothieno3,2-b1-benzothiophene (BTBT) were prepared by physical vapor transport.•Bottom contact/bottom gate field effect transistors based on BTBT single crystals were fabricated.•Mobility up to 3x10-2 cm2 V−1 s−1 was measured in good agreement with calculated mobilities.•Intermolecular interactions between simple BTBT cores are reduced in comparison with alkyl-substituted BTBTs.
On page 1180, T. Hegmann and team show that gold nanorods decorated with discotic liquid crystals self‐assemble into nanorod ribbons both in thin films on TEM grids as well as in the bulk. These ...nanorods can be aligned with over 75% efficiency based on the calculated order parameter and enhance the charge carrier mobility in the parent discotic liquid crystal host. The image shows the texture of the hexagonal columnar liquid crystal host H6TP doped with the functionalized gold nanorods at 1% by weight.
2D organic–inorganic perovskites are an emerging class of materials with great potential for optoelectronics since a wide variety of large functional chromophores can be regularly incorporated. Among ...this new type of materials, hybrid perovskite systems incorporating strong electron acceptor molecules are considered as a promising approach to designing a new type of functional 2D perovskites for optoelectronics. In this work, a rare example of organic–inorganic 2D perovskite incorporating strong acceptors such as naphthalene diimide (NDI) building blocks between inorganic sheets is presented. This hybrid architecture forms highly air‐stable thin films with a structure consisting of inorganic perovskite monolayers of metal‐halide octahedra separated by bilayers of NDI‐based organic cations. The presence of strong electron‐accepting moieties in this multifunctional donor–acceptor hybrid heterostructure leads to a rare type II heterojunction in which the excitons can be efficiently dissociated via the electron‐transfer process and in which holes and electrons can be easily confined in the inorganic and organic sublayers, respectively. Such an ultimate p–n heterojunction shows improved photoconduction properties with a photocurrent multiplied by ≈40 under white‐light illumination in comparison to a similar 2D perovskite structure containing optically and electrically inert alkyl chains as organic components.
A 2D perovskite incorporating strong acceptor naphthalene diimide (NDI) moities between inorganic sheets is prepared, leading to a multifunctional donor–acceptor hybrid type II heterostructure. In such an ultimate p–n heterojunction, excitons can be efficiently dissociated via the electron‐transfer process, and holes and electrons can be easily confined in the inorganic and organic sublayers, respectively, producing improved photoconduction properties.
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