RESUMO
The long-range ordering of bulk-heterojunctions (BHJs) significantly facilitates exciton diffusion and dissociation as well as charge transport. A feasible bio-inspired strategy to realize such a heterostructure is crystallization in gel media where the growing host crystals incorporate the surrounding guest materials of gel networks. Until now, the host-guest pairs forming ordered BHJs are still very limited and, more importantly, the used gel-network guests are structurally amorphous, spurring investigation toward crystalline gel-networks. Here, single crystals of fullerene and non-fullerene acceptors (NFAs) in poly(3-hexylthiophene) (P3HT) organogel are prepared, forming C60 :P3HT and (5Z,5â³Z)-5,5â³-((7,7â³-(4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-bâ³]dithiophene-2,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanylylidene))bis(3-ethyl-2-thioxothiazolidin-4-one) (O-IDTBR):P3HT BHJs. The crystalline P3HT network penetrates the crystal matrix without significantly disturbing the single crystallinity, resulting in long-range ordered BHJs. This bi-continuous structure, together with an improved overall ordering, contributes to enhanced charge/energy transfer. As a result, photodetectors based on these ordered BHJs exhibit ameliorated responsivity, detectivity, bandwidth, and stability as compared to the conventional BHJs with short-range ordering. Therefore, this work further extends the scope of long-range ordered BHJs toward crystalline polymer donors and NFAs, providing a generally applicable strategy for the design of organic optoelectronic devices with superior performance.
RESUMO
Polymer-templated nematic liquid crystal (LC) holographic gratings via visible-light recording are presented in the presence of reactive mesogens (RMs) and rose bengal (RB)/N-phenylglycine (NPG) photoinitiation systems. By optimizing the concentration of RMs in the polymer-templated LC gratings, the template after being washed out can be refilled with suitable fluidic components. And the dependence of the first-order diffraction efficiency (DE) on the concentration of RB and NPG molecules was discussed in detail. The polarization-dependency of diffraction properties was also investigated. It is revealed that the diffractive behaviors of polymer-templated LC gratings can be dynamically reconfigured by varying temperature or refilling organic solutions with different refractive index (RI). Furthermore, the potential for recording holograms using green light is explored. We expect that the reconfigurable polymer-templated LC gratings fabricated via visible-light interference would provide a facile approach to regulate the diffraction properties of holographic gratings apart from electric field, thus paving a way towards a class of novel anti-counterfeiting devices.
RESUMO
Recently, flexible electronics have been paid great attention due to their unique characteristics, such as high stretchability, arbitrary bending, and recoverable deformation. As a core component, flexible conductive materials with skin-like properties are desirable and valuable for the development of flexible electronics. However, the integration of skin-like mechanical properties, inherent self-healing ability, ultrahigh sensitivity, and electrical conductivity into one material is difficult to be realized. Here, this study reports a kind of conductive film (PAM-dc-fGO) fabricated by cross-linking intrinsic self-repair polyazomethine (PAM) and ethylenediamine-functionalized graphene oxide (fGO) through dynamic covalent bonds (imine bonds, -CHâN-). The as-prepared conductive films exhibit skin-like mechanical properties with a stretchability of 212-275% and elastic moduli of 0.76-4.23 MPa. In addition, the healing efficiency in mechanical properties of the 24 h healed specimen can restore up to 99%, and the healing efficiency in terms of electrical conductivity still maintains above 95% after five breaking/healing cycles, indicating an excellent capability of self-repair. Due to the ultrahigh sensing sensitivity with the gauge factor (GF) of 641, the PAM-dc-fGO film-based strain sensor can precisely detect the weak signals from the human body. Moreover, the remote monitoring of human motions with a long distance of about 100 cm has been successfully conducted by a PAM-dc-fGO proximity sensor. This work provides a new path for the development of multifunctional soft materials, and the sensors show great potential in health diagnoses and security protection applications.