Karolina Smolarek

Comparative studies of structural, thermal, optical, and electrochemical properties of azines with different end groups with their azomethine analogues toward application in (opto)electronics.

Two series of azines and their azomethine analogues were prepared via condensation reaction of benzaldehyde, 2-hydroxybenzaldehyde, 4-pyridinecarboxaldehyde, 2-thiophenecarboxaldehyde, and 4-(diphenylamino)benzaldehyde with hydrazine monohydrate and 1,4-phenylenediamine, respectively. The structures of given compounds were characterized by FTIR, (1)H NMR, and (13)C NMR spectroscopy as well as elemental analysis. Optical, electrochemical, and thermal properties of all compounds were investigated by means of differential scanning calorimetry (DSC), UV-vis spectroscopy, stationary and time-resolved photoluminescence spectroscopy, and cycling voltammetry (CV). Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). Influence of chemical structure of the compounds on their properties was analyzed.

Silver nanowires enhance absorption of poly(3-hexylthiophene)

Results of optical spectroscopy reveal strong influence of plasmon excitations in silver nanowires on the fluorescence properties of poly(3-hexylthiophene) (P3HT), which is one of the building blocks of organic solar cells. For the structure where a conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used as a spacer in order to minimize effects associated with non-radiative energy transfer from P3HT to metallic nanoparticles, we demonstrate over two-fold increase of the fluorescence intensity. Results of time-resolved fluorescence indicate that the enhancement of emission intensity can be attributed to increased absorption of P3HT. Our findings are a step towards improving the efficiency of organic solar cells through incorporation of plasmonic nanostructures.

Synthesis, photophysical properties and application in organic light emitting devices of rhenium(I) carbonyls incorporating functionalized 2,2′:6′,2′′-terpyridines

Several new rhenium(I) complexes [ReCl(CO)3(4′-R-terpy-κ2N)] incorporating 2,2′:6′,2′′-terpyridine-based ligands were successfully synthetized and characterized by IR, NMR (1H and 13C), UV-vis spectroscopy and single crystal X-ray analysis. The luminescent properties of [ReCl(CO)3(4′-R-terpy-κ2N)] were studied in solution and solid state, at 298 and 77 K. To better understand the photophysical properties of [ReCl(CO)3(4′-R-terpy-κ2N)], density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed. Preliminary studies towards application of these complexes in organic light emitting diodes (OLEDs) were carried out, including testing the possibility of electroluminescence intensity increase by including metallic nanowires in the structure design.

NCN-Coordinating Ligands based on Pyrene Structure with Potential Application in Organic Electronics

Five novel derivatives of pyrene, substituted at positions 1,3,6,8 with 4-(2,2-dimethylpropyloxy)pyridine (P1), 4-decyloxypyridine (P2), 4-pentylpyridine (P3), 1-decyl-1,2,3-triazole (P4), and 1-benzyl-1,2,3-triazole (P5), are obtained through a Suzuki-Miyaura cross-coupling reaction or CuI -catalyzed 1,3-dipolar cycloaddition reaction, respectively, and characterized thoroughly. TGA measurements reveal the high thermal stability of the compounds. Pyrene derivatives P1-P5 all show photoluminescence (PL) quantum yields (Φ) of approximately 75 % in solution. Solid-state photo- and electroluminescence characteristics of selected compounds as organic light-emitting diodes are tested. In the guest-host configuration, two matrixes, that is, poly(N-vinylcarbazole) (PVK) and a binary matrix consisting of PVK and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt %), are applied. The diodes show red, green, or blue electroluminescence, depending on both the compound chemical structure and the actual device architecture. In addition, theoretical studies (DFT and TD-DFT) provide a deeper understanding of the experimental results.