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Effect of Auxiliary Donors on 3,8-Phenothiazine Dyes for Dye-Sensitized Solar Cells
摘要： Phenothiazines are one of the more common dye scaffolds for dye-sensitized solar cells. However, these sensitizers are exclusively based on a 3,7-substitution pattern. Herein, we have synthesized and characterized novel 3,8-substituted phenothiazine dyes in order to evaluate the effect of auxiliary donor groups on the performance of this new dye class. The power conversion efficiency increased by 7%–10% upon insertion of an auxiliary donor in position 8 of the phenothiazine, but the structure of the auxiliary donor (phenyl, naphthyl, pyrene) had a low impact when electrodes were stained with chenodeoxycholic acid (CDCA) additive. In the absence of CDCA, the highest power conversion efficiency was seen for the phenyl-based sensitizer attributed to a higher quality dye-monolayer. By comparing the novel dyes to their previously reported 3,7- analogues, only subtle differences were seen in photophysical, electrochemical, and performance measurements. The most notable difference between the two geometries is a lowering of the oxidation potentials of the 3,8-dyes by 40–50 mV compared to the 3,7-analogues. The best auxiliary donor for the 3,8-phenothiazine dyes was found to be pyrenyl, with the best device delivering a power conversion efficiency of 6.23% (99 mW cm?2, 10 eq. CDCA, JSC = 10.20 mA cm?2, VOC = 791 mV, and FF = 0.765).
关键词： Geometry study,auxiliary donor,donor position,phenothiazine,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Novel asymmetrical phenothiazine for fluorescent detection of cyanide anions
摘要： Novel asymmetrical phenothiazine (PTZ) bearing 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)-malononitrile (OIM) moiety as the cyanide receptor was synthesized. The sensor fluorophore displayed an intramolecular charge transfer (ICT) electronic absorption peak at 500 nm and fluorescence peak at 576 nm in CH3CN:H2O (90:10) solution. When running a titration of the prepared phenothiazine fluorophore with a range of concentrations of cyanide, the electronic absorption and fluorescence peaks diminish in a ratio-metric mode. This can be attributed to the nucleophilic Michael-attack of cyanide anion at the α-position of the oxoindenylidenemalononitrile vinyl moiety of the fluorophore. This results in switching such electron acceptor to anionic electron donor and thus breaking the conjugated molecular system, which eventually influence the ICT and the emission peak position of the fluorophore. It was found that the fluorescent sensor displayed high sensitivity with a rapid responding time as low as than 50 second. A high selectivity was also detected toward cyanide ion at a recognition limit as low as 3.2 × 10?9 mol L-1.
关键词： Cyanide,Fluorescence,Phenothiazine,Nucleophilic addition,Knoevenagel condensation
更新于2025-09-10 09:29:36
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Dark-blue titanium dioxide: Effect of phenothiazine on structural and optical properties of nanocrystalline anatase TiO2
摘要： We studied the effect of the phenothiazine (PTZ) surface doping on the structural and optical properties of nanocrystalline titanium dioxide powder with a single anatase phase (A-TiO2). We found that the mixing and interaction of PTZ and A-TiO2 leads to the intense dark-blue color of PTZ-doped A-TiO2 (A/PTZ). The appearance of new bands in the Fourier transform IR spectrum indicated the formation of PTZ?+ radical cations and reduced Ti3+species as well as extra oxygen vacancies (VO) in the TiO2 matrix. The UV-vis absorption spectrum of A/PTZ exhibited a strong increase in absorption in the visible region (>400 nm). The doping of A-TiO2 with PTZ causes a noticeable redshift of the absorption edge and a significant narrowing of the band gap by 0.24 and 0.49 eV for direct and indirect electronic transitions, respectively. The photoluminescence spectra show that the photoluminescence originating from Ti3+ and [VO-Ti3+] states for A/PTZ is much stronger than for A-TiO2, but the excitonic photoluminescence of A/PTZ is quenched. An increased number of surface defects in A/PTZ can essentially increase the nonradiative charge recombination and photoluminescence quenching, and therefore may considerably enhance the photoactivity of the dark-blue TiO2 in the visible range of the spectrum.
关键词： Optical properties,Spectroscopy,Phenothiazine,Titanium dioxide,Nanostructures
更新于2025-09-09 09:28:46
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Photo-Physical Properties of Thermally Activated Delayed Fluorescent Materials upon Distortion of Central Axis of Donor Moiety
摘要： In this study, we showed the distortion of central axis of donor moiety can switch critically the rate of reverse intersystem crossing (kRISC) process, which is the trigger point to modulate the lifetime of delayed fluorescence. To achieve kRISC what we desired (105 to 106 s-1) in a series of donor-acceptor-donor (D-A-D) type thermally activated delayed fluorescence (TADF) materials, the donor groups (phenoxazine and phenothiazine) was selectively introduced. Maintaining the near orthogonality between donor and acceptor (benzonitrile) moiety, the occurrence of the distortion of central axis of donor moiety could make the effect of locally excited triplet state (3LE). In other words, the interaction between 3LE and the charge transfer counterparts (i.e., 1CT and 3CT) contributes an opposite propensity of kRISC for each target TADF materials when those are dissolved in solution and condensed in solid-state. Herein, we have theoretically and experimentally shown the photo-physical behavior of common D-A-D type TADF upon the different system.
关键词： Reverse Intersystem Crossing,Thermally Activated Delayed Fluorescence,Benzonitrile,Phenoxazine,Donor-Acceptor-Donor,Phenothiazine
更新于2025-09-09 09:28:46
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Synthesis of Novel Donor-Acceptor Type Molecule Based on Phenothiazine Unit for Organic Light-Emitting Materials
摘要： A novel conjugated organic molecule based on central phenothiazine unit as an electronic donor and aldehyde group termini as an electronic acceptor has been designed and constructed. Optical spectra show that, the absorption and fluorescence spectra of M2 are large red-shifted relative to M1 in both states, however, from solution to the solid state, the absorption maxima and emission maxima of M1 and M2 are in the opposite trends (blue-shift). The fluorescence spectra exhibit that the emission maxima of M1 and M2 which range from 485 nm to 588 nm belong to green light region. As expected, the target compounds should be a promising green light-emitting material for applications in organic light-emitting diodes (OLEDs).
关键词： Molecule,Donor-acceptor,Phenothiazine unit,Light-emitting materials
更新于2025-09-09 09:28:46