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.
Donor−acceptor (D−A) small molecules are regarded as promising hole-transporting materials for perovskite solar cells (PSCs) due to their tunable optoelectronic properties. This paper reports the ...design, synthesis and characterization of three novel isomeric D-π-A small molecules PY1, PY2 and PY3. The chemical structures of the molecules consist of a pyrazolo1,5-apyrimidine acceptor core functionalized with one 3,6-bis(4,4′-dimethoxydiphenylamino)carbazole (3,6-CzDMPA) donor moiety via a phenyl π-spacer at the 3, 5 and 7 positions, respectively. The isolated compounds possess suitable energy levels, sufficient thermal stability (Td > 400 °C), molecular glass behavior with Tg values in the range of 127−136 °C slightly higher than that of the reference material Spiro-OMeTAD (126 °C) and acceptable hydrophobicity. Undoped PY1 demonstrates the highest hole mobility (3 × 10−6 cm2 V−1 s−1) compared to PY2 and PY3 (1.3 × 10−6 cm2 V−1 s−1). The whole isomers were incorporated as doped HTMs in planar n-i-p PSCs based on double cation perovskite FA0.85Cs0.15Pb(I0.85Br0.15)3. The non-optimized device fabricated using PY1 exhibited a power conversion efficiency (PCE) of 12.41%, similar to that obtained using the reference, Spiro-OMeTAD, which demonstrated a maximum PCE of 12.58% under the same conditions. The PY2 and PY3 materials demonstrated slightly lower performance in device configuration, with relatively moderate PCEs of 10.21% and 10.82%, respectively, and slight hysteresis behavior (−0.01 and 0.02). The preliminary stability testing of PSCs is also described. The PY1-based device exhibited better stability than the device using Spiro-OMeTAD, which could be related to its slightly superior hydrophobic character preventing water diffusion into the perovskite layer.
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.
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.
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.
Clip chemistry: When a fully deterministic strategy that parallels polymer chemistry is used, mono‐, bi‐, and trifunctional clip‐bearing building blocks form noncovalent surface‐self‐assembled ...dimers, polymers, and 2D networks, respectively (see scheme). These entities can then be subjected to further higher‐level manipulations, as shown by controlled reorganization (cyclization) of a polymerlike chain around a molecular block.
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•Synthesis, mesomorphic and electrical properties of a thienothiophene derivative are presented.•Charge carrier transport was investigated in bulk, vacuum and solution deposited thin ...films.•Charge carrier transport was studied by temperature-dependent time-of-flight and in field-effect transistors.•The results show the potential of the melt-processing route for the high mobility organic semiconducting layer preparation.
A novel mesogenic 2,5-bis-(5-octylthiophene)-thieno3,2bthiophene (TT) derivative has been synthesized. The fused-ring thiophene, end-capped with two octylthiophenes, exhibits ordered lamellar mesophases which were characterized by polarizing optical microscopy, differential scanning calorimetry and small-angle X-ray diffraction at various temperatures. The charge transport properties were investigated by time-of-flight technique as a function of temperature. On cooling from isotropic phase, a maximum hole mobility value of 0.07cm2V−1s−1 was measured in the highly ordered mesophase of the bulk films. Field-effect transistor experiments on both solution and vacuum deposited thin films have also been performed. The solution-processed films exhibit charge carrier mobilities several orders of magnitude lower than values extracted from bulk time-of-flight curves and from vacuum deposited thin film transistors. This work provides evidence that the melt-processing route is an efficient alternative to commonly used solution-processing for fabrication of charge transporting layers from liquid crystalline semiconductors, with performances comparable to evaporation techniques.
Taking into account substrate crystallographic constraints, an overarching molecular binding motif has been designed to allow transferable self-assembling patterns on different substrates. This ...optimized clip demonstrates robust and equivalent self-assembled architectures on both highly oriented pyrolitic graphite (HOPG) and reconstructed Au(111) surfaces.
Controlled patterning of highly oriented pyrolitic graphite with well‐defined 3D nanostructures is realized by steered uniaxial alignment of multilayered 2.2paracyclophane‐based building blocks ...bearing functional clips (see picture). Their in‐plane self‐assembly allows exact positioning of vertical structural elements with precisely defined nanoscale spacing.
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