Comparison in optoelectronic properties of triphenylamine-imidazole or imidazole as donor for dye–sensitized solar cell: Theoretical approach

In the present work, the structural and electronic properties of the D-D'-π-A organic dye with two donors have been calculated theoretically by DFT/TD-DFT method. In order to prove their efficiency as sensitizers, a comparative study was performed with a serie of D-π-A architecture with one donor. The results of light harvesting efficiency (LHE), open circuit voltage (Voc), free energy injection (∆Ginj), free energy dye regeneration (∆Greg,) excited-state lifetimes for the two series reveal that the D-D'-π-A dyes are promising for the design of new sensitive dyes in solar cells.

Fused Thiazine Tethered Metal-Free Dyes for Dye Sensitized Solar Cells: A Computational Investigation

Three novel cyanoacetamide decorated phenothiazines (1a-c) have been designed. Structural and photo-physical properties of the molecules 1a-c have been investigated. To better realize the charge transport process involved in the dye-sensitized solar cells (DSSCs), computational studies have been performed using B3LYP and CAM-B3LYP method for the dyes 1a-c. Theoretical findings for DSSCs include LHE (light-harvesting efficiency) and driving forces such as electron injection (ΔGinject) and dye regeneration have been calculated to envisage the most appropriate dyes for the application of DSSC.

The impact of insufficient time resolution on dye regeneration lifetime determined using transient absorption spectroscopy

Dye regeneration lifetimes of a combination of dyes and redox mediators were determined by two transient absorption (TA) spectrometers with 0.5 ns (sub-ns) and 6 ns (ns) time resolutions to...

Effect of TiO2 Photoanodes Morphology and Dye Structure on Dye-Regeneration Kinetics Investigated by Scanning Electrochemical Microscopy

The dye regeneration in dye-sensitized solar cells (DSSCs) is improved by optimizing the charge separation at the level of the sensitized semiconductor treatment of the mesoporous electrode by TiCl4 that passivates the surface for back electron transfer reactions. The dye-regeneration kinetics is analyzed for DN216- and D358-sensitized porous TiO2 electrodes with and without a TiCl4 treatment by means of scanning electrochemical microscopy (SECM). Different mass transport limitation of the [Co(bpy)3]3+ mediator through the porous electrode is found for the comparison of the structurally similar dyes but cannot be detected for the thin layer introduced by the TiCl4 treatment. Phototransient measurements are conducted directly in the SECM cell without any intermediated sample manipulation. The results from those measurements corroborate the findings from steady state SECM measurements.

Ru(II) porphyrins as sensitizers for DSSCs: Axial vs. peripheral carboxylate anchoring group

In this study, two porphyrin chromophores metallated with ruthenium, RuTBP and RuTBPPy, were prepared and studied as sensitizers in dye-sensitized solar cells (DSSCs). The difference between the two dyes is the position (axial vs. peripheral) of the carboxylic anchoring group. This work examines the impact of this variation towards the optical, electrochemical and photovoltaic performance of DSSCs. The thorough photophysical and photovoltaic measurements indicated that the peripherally substituted sensitizer (RuTBP) presented higher photovoltaic performance compared to RuTBPPy. More specifically, DSSCs sensitized with RuTBP and RuTBPPy displayed an overall power conversion efficiency (PCE) of 5.12% and 4.08%, respectively. The higher PCE value of the DSSC sensitized with RuTBP is mainly attributed to the enhancement of [Formula: see text] and FF values. These factors were enhanced due to the efficient dye regeneration process, the suppression of back-charge recombination reactions and the longer electron lifetimes as evidenced from the electrochemical impedance spectra.

A tandem redox system with a cobalt complex and 2-azaadamantane-N-oxyl for fast dye regeneration and open circuit voltages exceeding 1 V

Tandem electrolyte systems with Co(bpy)33+/2+ and the organic radical 2-azaadamantane-N-oxyl reaching a VOC over 1 V were studied.

Theoretical study on electronic and absorption characters of p-type D-A-π-A triaryamine sensitizer

The structural and electronic properties of well-known 4,4′-(4-(5-(2,2-dicyanovinyl)thiophen-2-yl)phenylazanediyl)dibenzoic acid (O2) and its hypothetical dyes O3–O7 were investigated by computational techniques. The absorption properties were probed. By replacing the 2-methylidenepropanedinitrile acceptor with 1,3-diethyl-5-methylene-2-thioxo-dihydropyrimidine-4,6(1H,5H)-dione, the molecular orbital energy levels were well tuned. The modified dyes meet the basic requirements of both –ΔGinj and –ΔGreg being over 0.2 eV for an efficient hole injection and dye regeneration, respectively. All the designed p-type dyes O3–O7 have smaller energy gap and significant red shift in absorption spectra than that of the reference O2. Finally, our results suggested that O3–O7 have larger light-harvesting efficiencies (LHE) in the visible spectral regions of 400 nm to 700 nm than O2. Among all the dyes, O5 is expected to have an excellent performance as a p-type sensitized dye in solar cells due to its great LHE and sufficient hole injection efficiency.