Morphology and energy transfer study between conjugated polymers thin films: experimental and theoretical approaches.

In this paper, the effect of a silafluorene derivative copolymer, the poly[2,7-(9,9-dioctyl-dibenzosilole)-alt-4,7-bis(thiophene-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) sensitized by a simpler homopolymer, the poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) were investigated in a bilayer and ternary blend configuration. The energy transfer between the polymers prior to electron transfer to the acceptors can be an efficient alternative to photocurrent improvement in photovoltaic devices. The interactions between the two donor polymer films were evaluated optically and morphologically with several experimental techniques and correlated to the photovoltaic performance. Improved photon to charge conversion was observed in the blend films at different device geometries-considering bilayer devices with fullerene and inverted flexible devices blade coated in air conditions with a non-fullerene small molecule acceptor. Resonant Auger spectroscopy using the core-hole clock method was employed to evaluate the ultrafast charge delocalization times of conjugated polymers in the low-femtosecond regime. Density functional theory and time-dependent DFT methods were used to help understand some experimental observations. The results show that the homopolymer can improve the absorption spectra and the nonradiative-energy transfer from MDMO-PPV to PSiF-DBT and act as a photosensitizer in the copolymer units. In addition, the PSiF-DBT blended with MDMO-PPV exhibits a more organized structure than the neat material resulting in better absorption stability of films kept under continuous illumination.

Novel electrochemical sensor based on molecularly imprinted polymer for selective recognition of sesquiterpene ß-caryophyllene.

Molecularly imprinted polymers provide an excellent platform for the modification of selective electrodes for sensing applications. Herein, we present a novel modified carbon paste electrode (CPE) with a selective molecularly imprinted polymer (MIP) for recognition of sesquiterpene ß-caryophyllene, constituted of important plants oil-resins and extracts. The non-covalent MIP was synthesized using AA, EGDMA, and AIBN as a functional monomer, cross-linker and initiator agent, respectively. Structural and chemical characterization of the synthesized MIP was conducted through scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was possible to verify the functional features of the synthesized MIP related to the extraction process of the template molecule. The CPE modified with MIP for sesquiterpene ß-caryophyllene recognition was characterized by electrochemical techniques as cyclic voltammetry (CV) and square wave voltammetry (SWV). The highest selective recognition electrode enables to detect concentrations in the range between 1.5 × 10-7 and 7.5 × 10-7 M, showing great potential for applications in monitoring content of sesquiterpene ß-caryophyllene in technological processes and for predicting the quality of extracts, oils, and resins of plants.