An efficient and simple method for synthesizing all-conjugated diblock copolymer is reported, using Stille polycondensation of A-A (dithienosilole) and B-B (diketopyrrolopyrrole) monomers with a macro end-capping agent P3HT. Diblock and triblock copolymers were produced with a molar composition that was tuned via the macromonomer molar mass and feed ratio. The molar mass and topology of the macromolecules obtained are discussed on the basis of the Carothers equation, conversion and monomer ratio. Spectrophotometry and cyclic voltammetry were used to highlight the complementarity of block absorption and the donor-acceptor nature of copolymers. Finally, integration in solar cells has been successfully performed with efficiencies reaching 2%. The performances of the devices were molar composition dependent and revealed that performance enhancement provided by the low band-gap block absorption was balanced by the copolymer nano-structuration that shrinks the charge collection at electrodes.
An efficient strategy is described to prepare electron donor/acceptor hybrid nanoparticles by anchoring a low band-gap polymer onto zinc oxide spheres. Functional macromolecules, bearing triethoxysilane or catechol terminal groups, were synthesized by polycondensation, using a ternary blend reaction, i.e. mixing two monomers and an end-capper. Importantly, and in agreement with Carothers theory, the amount of end-capper allowed to control the chains molar mass. ZnO spherical nanoparticles were then grafted with the polymer chains and TEM images confirmed that core@shell materials were formed. The surface morphology of these hybrid materials was anchoring agent dependent. When silane functionalized polymers were used, cross-linked aggregates were obtained due to competition between self-condensation of silanes and reaction with ZnO surface hydroxyl groups. On the contrary, well-dispersed core-shell particles were synthesized with catechol polymers as anchoring agents. This grafting onto methodology led to patchy nanoparticles on which both zinc oxide and polymer surfaces were accessible. The optical 2 properties of the hybrid material were ascertained by UV-visible absorption and photoluminescence to show a specific quenching of the polymer fluorescence by the metal oxide.
The use of perylenediimide (PDI) building blocks in materials for organic electronic is of considerable interest. This popular n-type organic semiconductor is tuned by introducing peripheral groups in their ortho and bay positions. Such modifications radically alter their optoelectronic properties. In this article, we describe an efficient method to afford regioisomerically pure 1,6/7-(NO 2 ) 2 -and (NH 2 ) 2 -PDIs employing two key steps: the selective crystallization of 1,6-(NO 2 ) 2 -perylene-3,4,9,10-tetracarboxy tetrabutylester and the nitration of regiopure 1,7-Br 2 -PDI with silver nitrite. The optoelectronic properties of the resulting regioisomerically pure dinitro, diamino-PDIs and bisazacoronenediimides (BACDs) are reported and demonstrate the need to separate both regioisomers of such n-type organic semiconductors for their inclusion in advanced optoelectronic devices. For the first time, the two regioisomers of the same PDI starting material are available on the multigram scale, which will stimulate the exploration of regioisomerism/ properties relationship for this family of dyes.
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