Synthesis of free-standing two-dimensional (2D) conjugated covalent organic framework (COF) films linked by CÀCb onds is highly desirable.N ow av ery simple and mild strategy has been developed to synthesize them by Suzuki polymerization on aw ater-toluene interface in ar efrigerator. The versatility of this strategy was confirmed by the successful synthesis of two different 2D-COF films:ap orous graphene and aporphyrin-contained 2D-COF.Both 2D-COF films have large lateral sizeand their crystalline domains were visualized by high resolution TEM. Based on the wide compatibility of Suzuki reaction, our breakthrough work opened adoor for the synthesis of various 2D conjugated COF films.For application studies,t he porous graphene exhibits ag ood carrier mobility, which is muchh igher than À C = N À linked 2D COF films and agood catalytic activity for hydrogen evolution reaction, which is comparable with nitrogen-or phosphorus-doped graphene.

In this work, three small molecular donors (SMDs) S35, S35–1Si, and S35–2Si, with 3,5-difluorophenyl-substituted benzodithiophene as the central 2-dimensional unit to combine different numbers of siloxane-terminated side chain, were synthesized for all-small-molecule organic solar cells (ASM-OSCs). The three SMDs showed comparable film absorption peaks at 570 nm and optical band gaps of 1.8 eV. Relative to S35 and S35–1Si with symmetric alkyl side chains and asymmetric side chains on the central unit, respectively, the S35–2Si carrying two symmetric siloxane-terminated side chains displayed largely elevated melting and crystalline temperatures, lowered surface energy, and modulated molecular orientation. The three SMDs possessed edge-on dominated molecular orientations of their neat films; however, a big difference was found for their blend films with nonfullerene acceptor Y6. The S35:Y6 and S35–1Si:Y6 blends exhibited edge-on and face-on bimodal orientations but the S35–2Si:Y6 blend showed pure face-on orientation, indicating quite different donor:acceptor intermolecular interactions. Some large domains existed in the S35:Y6 and S35–1Si:Y6 blends, but could be suppressed by the S35–2Si:Y6 blend, leading to a more balanced charge transport. In ASM-OSCs, the two S35:Y6 and S35–1Si:Y6 active layers showed comparable power conversion efficiencies (PCE) of ∼12% but a much higher efficiency of 13.50% could be achieved with the S35–2Si:Y6 active layer. Our results suggest that the siloxane-terminated side chain is promising to regulate crystalline ability of a SMD, paving a way for high performance ASM-OSCs.

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1wileyonlinelibrary.com www.particle-journal.com www. MaterialsViews.com The "far-fi eld" effect of metal nanoparticles (NPs), when chromophores localized nearby metal NPs (typically the distance > λ /10), is an important optical effect to enhance emission in photoluminescence. The far-fi eld effect originates mainly from the interaction between origin emission and mirrorrefl ected emission, resulting in the increased irradiative rate of chromophores on the mirror-type substrate. Here, the far-fi eld effect is used to improve emission effi ciency of polymer light-emitting diodes (PLEDs). A universal performance improvement is achieved for the full visible light (red, green, blue) PLEDs, utilizing gold (Au) NPs to modify the indium tin oxide (ITO) substrates; this is shown by experimental and theoretical simulation to mainly come from the far-fi eld effect. The optimized distance, between the NPs and chromophores with visible light emission ranging from 400 to 700 nm, is 80-120 nm. Thus the scope of the far-fi eld may overlap the light-emitting profi le very well to enhance the effi ciency of optoelectronic devices. The 30-40% enhancement is obtained for different color-emitting materials through distance optimization. The far-fi eld effect is demonstrated to enhance device performance for materials in the full-visible spectral range, which extends the optoelectric applications of Au NPs.One of the most important methods to increase electroluminescence (EL) efficiency is increasing the photoluminescence (PL) effi ciency of active-layer materials, because the EL effi ciency is theoretically proportional to PL effi ciency. Driven by this motivation, scientists not only attempt different material structures of active layer but also search additional photophysical assistance during device fabrication for further enhancement. [ 10,11 ] Over the last decades, metallic nanostructures have been focused on improving the effi ciency of organic optoelectronic devices, [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] which is mainly based on the optical and electrical effects of metal nanoparticles (NPs), including local surface plasma-enhanced fl uorescence (LSPR), [ 12,13,17,19 ] electrical properties, [ 13,29 ] interface effect, [ 26 ] light scattering, [ 15 ] and so on.The "far-fi eld" effect of metal NPs is a very important optical effect for emission enhancement in PL besides the "nearfi eld" effect. [ 22,25,[31][32][33] The far-fi eld effect is quite different from the near-fi eld effect in working distance between metal NPs and fl uorophores. When the dye fi lm is brought into the proximity of the metal NPs-based substrate, two enhancement maximum would be observed as a function of the interlayer thickness. With the increasing of interlayer thickness, the fi rst enhancement maximum (near-fi eld effect) is observed at 5-10 nm spacer thickness. For longer distance, the enhancement of quantum yield is followed by a second maximum at 80-120 nm interlayer thicknesses, which is known as far-fi...

Synthesis of free-standing two-dimensional (2D) conjugated covalent organic framework (COF) films linked by CÀCb onds is highly desirable.N ow av ery simple and mild strategy has been developed to synthesize them by Suzuki polymerization on aw ater-toluene interface in ar efrigerator. The versatility of this strategy was confirmed by the successful synthesis of two different 2D-COF films:ap orous graphene and aporphyrin-contained 2D-COF.Both 2D-COF films have large lateral sizeand their crystalline domains were visualized by high resolution TEM. Based on the wide compatibility of Suzuki reaction, our breakthrough work opened adoor for the synthesis of various 2D conjugated COF films.For application studies,t he porous graphene exhibits ag ood carrier mobility, which is muchh igher than À C = N À linked 2D COF films and agood catalytic activity for hydrogen evolution reaction, which is comparable with nitrogen-or phosphorus-doped graphene. Angewandte Chemie Communications