Green Electroluminescence from Charged Phenothiazine Derivative

Abstract

A novel charged green-emitting organic small molecule, PPP, was synthesized and characterized by thermal, photophysical, electrochemical, and electroluminescence investigations. The theoretical properties of PPP were confirmed by means of computational studies. PPP exhibits a good thermal decomposition temperature of 355 °C. The compound PPP shows positive solvatochromism upon increasing the solvent polarity due to the more polarized excited state arising from the intramolecular charge transfer in the excited state. Solid-state emission of PPP was slightly red-shifted compared to that of its solution emission spectrum, showing the reduced intermolecular interaction in the solid state. Solution-processed LEC devices were fabricated using PPP as a neat light-emitting layer. The fabricated single-component light-emitting electrochemical cell devices exhibited green electroluminescence centered at 530 nm with the CIE coordinates of (0.32, 0.58). Electroluminescent devices operated at very low turn-on voltages reveal a maximum luminance of 499 cd/m2. These promising results are highly desirable for the development of low-cost lighting devices.

Synthesis and Photophysical Investigation of Phenothiazine Derivative

“…The calculated LUMO energy level was found to be -2.32 eV. Compared with the previous molecule [21] reduced HOMO and LUMO energy levels were obtained for sulfone derivative which attributed from the strong electron affinity of sulfone unit. This results were revealed that change in the oxidation state of sulfur lowers the energy level of the molecule.…”

“…Recently, charged small molecules were successfully utilized as light-emitting material and serves dual role in LECs. [12][13][14][15][16][17][18][19][20][21] In this study, we report synthesis and photophysical characterization of sulfone form of charged naphthalene-phenothiazine derivative. The oxidized form of molecule resulted high thermal stabilities and blue emission in both solution as well as in thin-films.…”

Effect of donor substituents on thermally activated delayed fluorescence of diphenylsulfone derivatives

“…Stokes shift of 1 is sufficiently small to allow self-quenching by Förster resonance energy transfer (FRET) [19][20]. Two main effects lead to the large Stokes shifts up to 300 nm observed for the solutions of 2-4 in polar THF: (i) intramolecular charge transfer (ICT) due to almost orthogonal inter-ring geometry between donor and acceptor; (ii) strong electron donating ability of phenothiazine, phenoxazine and acridane moieties 21. Replacement of the solvent with the less polar one (THF (ε r =7.5) → chloroform (ε r =4.81) → toluene (ε r =2.38)) leads to the hypsochromic shift of the emission peaks which is the evidence of ICT nature.Considering the potential application of compounds 1-4 as emitters in OLEDs, photophysical properties of solid films of molecular mixtures of 1-4 with mCP and TCz1 were studied.…”

Low‐Cost, Organic Light‐Emitting Electrochemical Cells with Mass‐Producible Nanoimprinted Substrates Made Using Roll‐to‐Roll Methods

“…[7][8][9][10][11][12][13] PLECs have simple singlelayer structures, which can be fabricated using roll-to-roll methods, using solutions containing both FCPs and ion conductors. [11,[22][23][24][25][26][27] Realizing high efficiency organic lighting will require more effective light outcoupling technologies. [7][8][9][10]20] PLECs have many other advantages, e.g., they can be fabricated using air-stable electrodes and thicker active layers.…”

“…In addition, it has been reported that certain low-molecularweight compounds, such as pentacene, carbene, and metal complexes, can be used to enable color tuning and improve efficiency. [11,[22][23][24][25][26][27] Realizing high efficiency organic lighting will require more effective light outcoupling technologies. [28][29][30][31][32][33][34][35][36] This is because in conventional organic light-emitting devices, ≈80% of the emitted light is optically trapped between the ITO and organic layers (ITO/organic modes) and in the glass substrate (substrate modes) and lost, and only around 20% of the emitted light can typically be extracted from the devices.…”