Novel D-π-A organic sensitizers containing diarylmethylene-bridged triphenylamine and different spacers for solar cell application

Synthetic Efforts to Investigate the Effect of Planarizing the Triarylamine Geometry in Dyes for Dye-Sensitized Solar Cells

The geometry of a dye for dye-sensitized solar cells (DSSCs) has a major impact on its optical and electronic properties. The dye structure also dictates the packing properties and how well the dye insulates the metal-oxide surface from oxidants in the electrolyte. The aim of this work is to investigate the effect of planarizing the geometry of the common triarylamine donor, frequently used in dyes for DSSC. Five novel dyes were designed and prepared; two employ conventional triarylamine donors with thiophene and furan π-spacers, two dyes have had their donors planarized through one sulfur bridge (making two distinct phenothiazine motifs), and the final dye has been planarized by forming a double phenoxazine. The synthesis of these model dyes proved to be quite challenging, and each required specially designed total syntheses. We demonstrate that the planarization of the triarylamine donor can have different effects. When planarization was achieved by a 3,7-phenothiazine and double phenoxazine structures, improved absorption properties were noted, and a panchromatic absorption was achieved by the latter. However, an incorrect linking of donor and acceptor moieties has the opposite effect. Further, electrochemical impedance spectroscopy revealed clear differences in charge recombination depending on the structure of the dye. A drawback of planarized dyes in relation to DSSC is their low oxidation potentials. The best photovoltaic performance was achieved by 3,7-phenothazine with furan as a π-spacer, which produces a power conversion efficiency of 5.2% (J _sc = 8.8 mA cm^-2, V _oc = 838 mV, FF = 0.70).

Novel Dyes Design Based on First Principles and the Prediction of Energy Conversion Efficiencies of Dye-Sensitized Solar Cells

With the depletion of fossil energy, solar energy has gradually attracted people's attention. Dye-sensitized solar cells have developed rapidly in recent years due to their low cost and high conversion efficiency. In this article, based on the theoretical research on the photovoltaic parameters of DSSCs in the early stages of the research team, we have made an accurate prediction of J sc, V oc, and PCE of C286. (The error in our predicted PCE values was 3.33% relative to the experiment.) Also, we further designed a series of new dyes CH1-CH5 by introducing donors and co-acceptors with C286-C288 as the prototype using the DFT/TDDFT method. The PCE of the designed dyes CH2-CH5 exceed the given dye C286, especially the CH3 and CH4 obtained the PCE of 26.2 and 14.5%. This indicates the proposed dyes offer a dramatic improvement on PCE for DSSC devices. Moreover, the designed dyes such as CH3 and CH4 have great potential to be applied to photovoltaic applications, further enabling the design of novel, highly efficient photoactive materials.

A Spherically Shielded Triphenylamine and Its Persistent Radical Cation

This work reports the design and synthesis of a sterically protected triphenylamine scaffold which undergoes one-electron oxidation to form an amine-centered radical cation of remarkable stability. Several structural adjustments were made to tame the inherent reactivity of the radical cation. First, the parent propeller-shaped triphenylamine was planarized with sterically demanding bridging units and, second, protecting groups were deployed to block the reactive positions. The efficiently shielded triphenylamine core can be reversibly oxidized at moderate potentials (+0.38 V, vs. Fc/Fc+ in CH2 Cl2 ). Spectroelectrochemistry and chemical oxidation studies were employed to monitor the evolution of characteristic photophysical features. To obtain a better understanding of the impact of one-electron oxidation on structural and electronic properties, joint experimental and computational studies were conducted, including X-ray structural analysis, electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. The sterically shielded radical cation combines various desirable attributes: A characteristic and unobstructed absorption in the visible region, high stability which enables storage for weeks without spectroscopically traceable degradation, and a reliable oxidation/re-reduction process due to effective screening of the planarized triphenylamine core from its environment.

Blue emissive dimethylmethylene-bridged triphenylamine derivatives appending cross-linkable groups

Blue-emissive and cross-linkable dimethylmethylene-bridged triphenylamine derivatives were synthesized and their optical and electrochemical properties were investigated.

Design, Electron Transfer Process, and Opto-Electronic Property of Solar Cell Using Triphenylamine-Based D-π-A Architectures

A series of D-π-A type dyes were designed based on the experimentally synthesized A1 by introducing different functional groups on the donor and π-spacer, and the optical and electrical properties were calculated by using density functional theory (DFT) and time-dependent DFT (TD-DFT). P1⁻P6 present highest light harvesting efficiency (LHE), driving force of electron injection ( Δ G i n j e c t ), reorganization energy ( Δ G r e g ) and e V O C . These critical parameters have a close relationship with the short-circuit current density ( J S C ) and open-circuit photovoltage ( V O C ), and lead to P1⁻P6 will exhibit higher efficiency. D4 also exhibit superior properties in the driving force of electron injection ( Δ G i n j e c t ), reorganization energy ( Δ G r e g ), which will lead to a higher short-circuit current density ( J S C ). We hope that these results will be helpful for experiments to synthesize new and highly efficient dyes.

Phenothiazine derivatives as photoredox catalysts for cationic and radical photosensitive resins for 3D printing technology and photocomposite synthesis

New phenothiazine derivatives are synthesized and proposed as high performance visible light photoinitiators.

A new class of triphenylamine-based novel sensitizers for DSSCs: a comparative study of three different anchoring groups

Triphenylamine-based dyes with chloro groups suitably placed on their π-linkers affect DSSC efficiency.

Carbazole-based compounds containing aldehyde and cyanoacetic acid: optical properties and applications in photopolymerization

Carbazole-based aldehyde and cyanoacetic acid containing dyes were synthesized and applied as photosensitizers in photopolymerization with a LED light source at 455 nm.

Synthesis, photophysics, ion detection and DFT investigation of novel cyano-substituted red-light chromophores with a triphenylamine donor

A series of novel triphenylamine-based red-light chromophores with multiple electron-withdrawing cyano substituents were synthesized by the Knoevenagel condensation reaction and characterized in detail.

Thiophene-substituted phenothiazine-based photosensitisers for radical and cationic photopolymerization reactions under visible laser beams (405 and 455 nm)

In the present work, we designed and prepared six new thiophene-substituted phenothiazine-based visible photosensitizers (ThPTZs) to solve the low absorptivity of phenothiazine in the visible light region.

Small molecule based N-phenyl carbazole substituted diketopyrrolopyrroles as donors for solution-processed bulk heterojunction organic solar cells

We report two acetylene-bridged small molecules DPP5 and DPP6 with low HOMO–LUMO gaps as donors along with PC₇₁BM as an acceptor for the fabrication of solution-processed bulk heterojunction solar cells.