Preparation and Photoluminescent Properties of Three 5-Amino Benzothiadiazoles (5-amBTDs)

Three D-A compounds were designed and synthesized based on a benzothiadiazole acceptor. Azepane (AP), iminodubenzyl (IDB) and iminostilbene (ISB) were used, respectively, as donors and installed on the 5-position of BTD to afford 1, 2 and 3, respectively. Their photophysical properties in different states (solution, film, crystal, and powder) are systematically investigated. Among them, AIE-active compounds 2 and 3 were found to have good sensitivity toward viscosity and display quite good linear relationship with an increase in viscosity. Compound 2 displayed dual emission in solutions which largely depended on the polarity of the solvent. Meanwhile, compound 2 exhibits a mechanochromic character with disappearance and reappearance of a dual-emissive peak induced by mechanical grinding and solvent fuming. Furthermore, these three compounds can be used in the fabrication of blue OLED devices.

Aggregation-induced enhanced emission-type cruciform luminophore constructed by carbazole exhibiting mechanical force-induced luminescent enhancement and chromism

One D-A type cruciform luminophore MDCS-BC based on carbazole has been prepared. We observed that this compound exhibits unique intramolecular charge-transfer (ICT) and typical aggregation-induced enhanced emission (AIEE) properties with the solid-state luminescence efficiency of 0.184. Moreover, this luminophore shows a significant stimuli-induced emission enhancement and chromism effect with good reversibility. Upon grinding, the fluorescence color of the as-prepared samples can change from blue (454 nm) to green (504 nm). What is unexpected is that the fluorescence efficiency of the initial powder is dramatically increased from 0.184 to 0.424 upon grinding. The results of PXRD, DSC and spectral properties studies show that the mechanical force-induced luminescence enhancement and chromism behavior of MDCS-BC originates from the transition between crystal and amorphous morphology, and the large red-shift and the emission enhancement inducing by grinding may be attributed to the planarization of the molecular conformation and subsequent planar ICT process.

The integrated adjustment of chlorine substitution and two-dimensional side chain of low band gap polymers in organic solar cells

The chlorination and side-chain extension of benzothiadiazole derivatives can finely manipulate the open-circuit voltage in their solar cells.

Synthesis, photophysical and thin-film self-assembly properties of novel fluorescent molecules with carbon-carbon triple bonds

Three novel fluorescent molecules with carbon-carbon triple bonds 2TBEA, 2TBDA and TEPEB are successfully designed and synthesized. Their thermal, photophysical, electrochemical, electronic and thin-film self-assembly properties were characterized. Three dyes showed typical photoluminescence (PL) emission behaviors, the PL intensities firstly increased and then decreased with gradually decreasing concentration. The appealing fluorescence properties indicated that three dyes could be used as good fluorescent materials. Additionally, the thin-film self-assembly behaviors of three dyes were also investigated. The microstructures of their optical microscopy (OM) images exhibited high flexibility. Furthermore, SEM and AFM surface morphology of these self-assembly nanostructures revealed that three well-defined long-range order of rod-like and tube-like self-assembly systems exhibited interesting morphology properties. Therefore, three compounds may be of great interest for the development of organic thin-film materials.

Small band gap D-π-A-π-D benzothiadiazole derivatives with low-lying HOMO levels as potential donors for applications in organic photovoltaics: a combined experimental and theoretical investigation

Small organic molecules with potential applications as donors in OPV featuring carbazole, benzocarbazole as donors, benzothiadiazole as acceptor and fluorene, thiophene as spacers (π) have been synthesized and characterized.

Monodisperse Low-Bandgap Macromolecule-Based 5,5'-Bibenzo[c][1,2,5]thiadiazole Swivel Cruciform for Organic Solar Cells

A novel low bandgap star-like macromolecule was synthesized and applied as electron donor material in the bulk heterojunction solar cells, in which the 5,5'-bibenzo[c][1,2,5]thiadiazole was used as the central node, in conjunction with four conjugated donor-acceptor arms. Compared with the corresponding small molecule with first generation arms, the macromolecule with second generation branches exhibited significantly enhanced photovoltaic device performances (blended with PC71BM as the active layer) due to dramatically improved short-circuit current density (J_sc) and fill factor (FF). The improvement in J_sc and FF can be attributed to the more broad absorption and the more favorable phase separation when comparing a monodisperse macromolecule with the second generation arms (SFTBT) with a small molecule with first generation branches (DFTBT).