Synthesis, characterization, and photovoltaic properties of novel conjugated copolymers derived from phenothiazines

Structural Geometry Variation of 1,4-Naphthalene-Based Co-Polymers to Tune the Device Performance of PVK-Host-Based OLEDs

Blue-color-emitting organic semiconductors are of significance for organic light-emitting diodes (OLEDs). In this study, through Suzuki coupling polymerization, three 1,4-naphthalene-based copolymers-namely, PNP(1,4)-PT, PNP(1,4)-TF, and PNP(1,4)-ANT-were designed and synthesized. The variation of comonomers, phenothiazine (PT), triphenylamine substituted fluorene (TF), and anthanthrene (ANT), effectively tuned the emitting color and device performance of poly(9-vinyl carbazole) (PVK)-based OLEDs. Especially, the polymer PNP(1,4)-TF, bearing perpendicular aryl side groups, showed a most twisted structural geometry, which enabled an ultra-high thermal stability and a best performance with blue emitting in PVK-host-based OLEDs. Overall, in this work, we demonstrate a promising blue-color-emitting polymer through structural geometry manipulation.

Synthesis and structural properties of 2-((10-alkyl-10H-phenothiazin-3-yl)methylene)malononitrile derivatives; a combined experimental and theoretical insight

BACKGROUND

Donor acceptor moieties connected through π-conjugated bridges i.e. D-π-A, in order to facilitate the electron/charge transfer phenomenon, have wide range of applications. Many classes of organic compounds, such as cyanine, coumarin carbazole, indoline, perylene, phenothiazine, triphenylamine, tetrahydroquinoline and pyrrole can act as charge transfer materials. Phenothiazines have been extensively studied as electron donor candidates due to their potential applications as electrochemical, photovoltaic, photo-physical and DSSC materials.

RESULTS

Two phenothiazine derivatives, 2-((10-hexyl-10H-phenothiazin-3-yl)methylene)malononitrile (3a) and 2-((10-octyl-10H-phenothiazin-3-yl)methylene)malononitrile (3b) have been synthesized in good yields and characterized by various spectroscopic techniques like FT-IR, UV-vis, (1)H-NMR, (13)C-NMR, and finally confirmed by single crystal X-ray diffraction studies. Density functional theory (DFT) calculations have been performed to compare the theoretical results with the experimental and to probe structural properties. In order to investigate the excited state stabilities the absorption studies have been carried out experimentally as well as theoretically.

CONCLUSIONS

Compound 3a crystallises as monoclinic, P2 (1)/a and 3b as P-1. The X-ray crystal structures reveal that asymmetric unit contains one independent molecule in 3a, whereas 3b exhibits a very interesting behavior in having a higher Z value of 8 and four independent molecules in its asymmetric unit. The molecular electrostatic potential (MEP) mapped over the entire stabilized geometries of the molecules indicates the potential sites for chemical reactivities. Furthermore, high first hyperpolarizability values entitle these compounds as potential candidates in photonic applications.Graphical abstractPhenothiazines; a comparison of experimental and theoretical analysis.

Photoemission Studies on N-Substituted Dithienylated Phenothiazines

Dithienylated phenothiazines (DTPTs) with different functional groups attached to the central nitrogen atom are presented as a class of versatile metal-free chromophores for the design of dye-sensitized solar cells (DSSCs) and organic light-emitting diodes (OLEDs). The electronic characteristics of spin-coated thin films on polycrystalline gold were studied using photoelectron spectroscopy assisted by theoretical calculations, scanning force microscopy, and UV/Vis spectroscopy. Complementary fluorescence spectra show light emission in the blue region (465 nm). The absorption properties and good hole-transporting abilities make DTPTs feasible hole-transporting materials (HTM) and metal-free chromophores in UV-sensitive solar cell designs.