Dithieno[3,2-a:3',2'-j][5,6,11,12]chrysene diimides: a versatile electron-deficient building block for polymeric semiconductors

In this work, dithieno[3,2-a:3',2'-j][5,6,11,12]chrysene diimides (DTCDI), an electron-deficient π-building block, were firstly incorporated into polymer main chains by using the 3,9-positions of chrysene and the α,α'-positions of thiophene units of DTCDI to connect with the 2,2'-bithiophene unit, affording copolymers P1 and P2, respectively. Due to their different connection ways the two polymers feature different optoelectronic properties.

A fluorescent and colorimetric probe based on naphthalene diimide and its high sensitivity towards copper ions when used as test strips

Herein, a red fluorescent and colorimetric probe (NDI-Py) based on naphthalene diimide was designed and synthesized, which exhibited rapid response, high sensitivity and selectivity towards copper ions, and the detection limit was as low as 0.97 μM in solution. Furthermore, NDI-Py demonstrated a strong red emission in the aggregated state because of its non-planar structure. Thus, it can act as a test strip to conveniently monitor copper ions with the detection limit as low as 2.0 μM.

A red fluorescent and colorimetric probe (NDI-Py) exhibited high selectivity and sensitivity towards copper ions both in solution and on silica gel plates.

Monomer stoichiometry imbalance-promoted formation of multisubstituted polynaphthalenes by palladium-catalyzed polycouplings of aryl iodides and internal diynes

A novel palladium-catalyzed polymerization route toward multisubstituted polynaphthalenes with high thermal stability and advanced functionalities in a monomer stoichiometry imbalance-promoted manner.

Fine-Tuning of Photophysical and Electroluminescence Properties of Benzothiadiazole-Based Emitters by Methyl Substitution

New benzothiadiazole-based materials containing methyl substitution are prepared and characterized as promising green/yellowish green emitters for electroluminescent applications. The dyes exhibited shorter wavelength absorption and emission when compared to nonmethylated dyes. A dye containing methyl group on the donor side exhibited blue shift in absorption and emission when compared to the analogous dye containing methyl group away from donor. The steric effect exerted by the methyl group is responsible for the nonplanar arrangement of donor and acceptor, which inhibited the intramolecular charge transfer. All the dyes displayed solvatochromism in the emission spectra characteristic of hybridization of local and charge transfer excited states. Due to the benefit of methyl group, the dyes restrained the formation of aggregates in the solid state. Solution processed multilayered OLED device were fabricated employing these compounds either as host emitters or dopant emitters in suitable host matrix and exhibited green/yellowish green electroluminescence with external quantum efficiency as high as 4.6% (15.7 cd A^-1).

Charge carrier mobility in one-dimensional aligned π-stacks of conjugated small molecules with a benzothiadiazole central unit

A theoretical study is applied to gain insight into the microscopic electron and hole transport in benzothiadiazole-cored molecular semiconductors either with furan or thiophene flanks arranged in π-stacks. For the characterization of the energetics of the reduction and oxidation processes and their impact on the molecular geometry, the internal reorganization energy is defined for isolated molecules in the gas phase. The outer-shell reorganization energy is evaluated within the frequency-resolved cavity model and as an electrostatic contribution within the polarizable continuum model. The intermolecular electronic coupling interaction for the Marcus charge hopping is calculated using the energy splitting in dimer method, the generalized Mulliken-Hush approach and the fragment charge difference scheme. In order to probe the relation between the charge hopping rate/charge carrier mobility and the molecular organization within the π-stacks, different stacking modes are investigated: (i) dimers with a perfect registry, i.e. segregated stacking motif, when molecules are placed face-to-face, and (ii) dimers forming slipped cofacial orientations with longitudinal and transverse shifts, i.e. mixed stacking motif. Besides, the effects of molecular planarity and rigidity, influencing internal molecular relaxation upon charging, the effects of non-covalent interactions within stacks and the heteroatom replacement on the charge carrier mobility are studied. The results obtained in the simulations of one-dimensional aligned π-stacks of molecular semiconductors are compared with available experimental data for small conjugated benzothiadiazole-cored molecules with thiophene flanks and benzothiadiazole-quaterthiophene-based copolymers.

Synthesis of largely π-extended naphthalenediimides via C–H activation towards highly soluble and narrow band-gap organic optoelectronic materials

Largely π-extended naphthalenediimides were synthesized by using efficient palladium catalyzed C–H/C–H homocouplings, with the yields of up to 94%.

Iridium-catalyzed polymerization of benzoic acids and internal diynes: a new route for constructing high molecular weight polynaphthalenes without the constraint of monomer stoichiometry

A green and powerful polymerization tool for constructing functional multisubstituted polynaphthalenes without strict control on monomer stoichiometry.

Lactone-fused electron-deficient building blocks for n-type polymer field-effect transistors: synthesis, properties, and impact of alkyl substitution positions

Dilactone-based Pechmann dyes were incorporated into conjugated polymers for n-type field-effect transistors, providing a new design concept of electron-deficient building blocks for polymer semiconductors.

Conjugated donor–acceptor terpolymers entailing the Pechmann dye and dithienyl-diketopyrrolopyrrole as co-electron acceptors: tuning HOMO/LUMO energies and photovoltaic performances

Three new conjugated D–A terpolymers with the Pechmann dye derivative and dithienyl-diketopyrrolopyrrole as co-acceptors are presented for photovoltaic studies.