Machine Learning Assisted Bithiophene Based Donor Acceptor Selection to Design New Fluoresent Dyes for Photovoltaic Applications

This study investigates the electronic properties and photovoltaic (PV) performance of newly designed bithiophene-based dyes, focusing on their light harvesting efficiency (LHE), open-circuit voltage (Voc), fill factor (FF), and short-circuit current density (Jsc).These new dyes are designed with the help of machine learning (ML) to design best donor acceptor designs. For this, we collect 2567 differenr electron donor groups and calculated their bandgap with the help of Random Forest (RF) Regression method. Their maximum absorption (λmax) values are redshifted with their 367-501 nm range having TA1 with higher value. Their LHE values range from 52 to 89%, with TA3 demonstrating the highest efficiency. Their Voc values varies significantly, with TA2 achieving the highest at 1.584 V, while TA5 and TA6 exhibit lowest values. Their FF)from 25.9 for TA4 to 59.3 for TA3, highlighting the superior charge extraction capabilities. Their Jsc values further reflect their performance potential, with TA1 leading at 39.43 mA/cm², while TA4 and TA6 show significantly lower values of 3.28 and 4.40 mA/cm², respectively. Overall, the findings suggest that the bithiophene-based dyes, particularly TA2 and TA3, possess promising characteristics for enhancing the efficiency of solar cells.

Theoretical investigation of the structural and spectroscopic properties of expanded metalloporphyrin complexes

The frontier molecular orbitals, UV-Vis absorption spectra, charge transfer (CT) and triplet excited states of 12 expanded D-A porphyrin/benzoporphyrin complexes were investigated using the density functional theory (DFT) method and time-dependent DFT in this work. The results showed that thiophene was an effective fragment for absorption of 'long wavelength', while the benzoporphyrin worked on the 'short wavelength', which was derived from its saddle-shaped structure; this expanded D-A conjugated system had a mild CT process with anthraquinone/isoindigo as acceptors and a strong CT process with naphtoquinone as acceptor. In addition, based on the simulation of the triplet state, the theoretical phosphorescence wavelength range of this series of derivatives was between 1000 and 1200 nm. This study is expected to assist the design of conjugated porphyrin for the field of porphyrin chemistry.

Push-Pull Zinc Porphyrins as Light-Harvesters for Efficient Dye-Sensitized Solar Cells

Dye-sensitized solar cell (DSSC) has been attractive to scientific community due to its eco-friendliness, ease of fabrication, and vivid colorful property etc. Among various kinds of sensitizers, such as metal-free organic molecules, metal-complex, natural dyes etc., porphyrin is one of the most promising sensitizers for DSSC. The first application of porphyrin for sensitization of nanocrystaline TiO2 can be traced back to 1993 by using [tetrakis(4-carboxyphenyl) porphyrinato] zinc(II) with an overall conversion efficiency of 2.6%. After 10 years efforts, Officer and Grätzel improved this value to 7.1%. Later in 2009, by constructing porphyrin sensitizer with an arylamine as donor and a benzoic acid as acceptor, Diau and Yeh demonstrated that this donor-acceptor framwork porphyrins could attain remarkable photovoltaic performance. Now the highest efficiencies of DSSC are dominated by donor-acceptor porphyrins, reaching remarkable values around 13.0% with cobalt-based electrolytes. This achievement is largely contributed by the structural development of donor and acceptor groups within push-pull framwork. In this review, we summarized and discussed the developement of donor-acceptor porphyrin sensitizers and their applications in DSSC. A dicussion of the correlation between molecular structure and the spectral and photovoltaic properties is the major target of this review. Deeply dicussion of the substitution group, especially on porphyrin's meso-position were presented. Furthermore, the limitations of DSSC for commercialization, such as the long-term stability, sophisticated synthesis procedures for high efficiency dye etc., have also been discussed.

Molecular Engineering of Zinc-Porphyrin Sensitisers for p-Type Dye-Sensitised Solar Cells

Design of novel efficient light-harvesters for p-type dye-sensitised solar cells (DSSCs) is indispensable for further advances in this photovoltaic technology. Herein, a novel D-π-A (D=donor, π=π-conjugated linker, A=acceptor) sensitiser, ZnP1, featuring an electron acceptor, perylenemonoimide (PMI), connected to an electron donor, di(p-carboxyphenyl)amine (DCPA), through fluorene and a zinc(II) porphyrin with alkyl chains as a π-conjugated bridge is introduced. Spectroscopic and electrochemical characterisation of this dye along with a newly synthesised PMI-free reference dye ZnP0 has been undertaken to demonstrate strong electron coupling between the DCPA donor and PMI acceptor subunits through the porphyrin ring in ZnP1, which redshifts the light absorption onset to the near-IR region. When integrated into p-DSSCs based on a mesoporous nickel(II) oxide semiconductor electrode and a tris(acetylacetonato) iron(III/II) redox mediator, ZnP1 exhibits an onset of the incident photon-to-current conversion efficiency at 800 nm and a power conversion efficiency of up to 0.92 % under simulated 100 mW cm^-2 AM 1.5 G irradiation. This is the highest efficiency of the porphyrin-based p-DSSCs hitherto reported.

Theoretical design of porphyrin sensitizers with different acceptors for application in dye-sensitized solar cells

Using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, three porphyrin dyes with different acceptors, such as carboxylic acid, cyanoacrylic acid, and 2-cyano-N-hydroxyacrylamide, have been designed. Compared to the best sensitizer (YD2-o-C8) so far, these designed dyes have small highest occupied orbital to lowest unoccupied orbital (HOMO–LUMO) band gaps, and wide absorptions with large oscillator strength at porphyrin Q bands. And the designed Dye1 is similar to YD2-o-C8 in electronic coupling with TiO₂, while improved Dye2 and Dye3 are better than YD2-o-C8, thus, Dye2 and Dye3 will be much faster for electron injection in dye-sensitized solar cell systems based on their long-term stable and efficient anchor groups. All these features show that our designed dyes, especially Dye2 and Dye3, have better absorption performance and faster electron injection. In addition, our results point out that 2-cyano-N-hydroxyacrylamide is a new promising acceptor. This study is expected to assist the molecular design of new efficient dyes for the advancement of dye-sensitized solar cells.

Using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, three porphyrin dyes with different acceptors, such as carboxylic acid, cyanoacrylic acid, and 2-cyano-N-hydroxyacrylamide, have been designed.

Photoelectrochemical Water Splitting System--A Study of Interfacial Charge Transfer with Scanning Electrochemical Microscopy

Fast charge transfer kinetics at the photoelectrode/electrolyte interface is critical for efficient photoelectrochemical (PEC) water splitting system. Thus, far, a measurement of kinetics constants for such processes is limited. In this study, scanning electrochemical microscopy (SECM) is employed to investigate the charge transfer kinetics at the photoelectrode/electrolyte interface in the feedback mode in order to simulate the oxygen evolution process in PEC system. The popular photocatalysts BiVO4 and Mo doped BiVO4 (labeled as Mo:BiVO4) are selected as photoanodes and the common redox couple [Fe(CN)6](3-)/[Fe(CN)6](4-) as molecular probe. SECM characterization can directly reveal the surface catalytic reaction kinetics constant of 9.30 × 10(7) mol(-1) cm(3) s(-1) for the BiVO4. Furthermore, we find that after excitation, the ratio of rate constant for photogenerated hole to electron via Mo:BiVO4 reacting with mediator at the electrode/electrolyte interface is about 30 times larger than that of BiVO4. This suggests that introduction of Mo(6+) ion into BiVO4 can possibly facilitate solar to oxygen evolution (hole involved process) and suppress the interfacial back reaction (electron involved process) at photoanode/electrolyte interface. Therefore, the SECM measurement allows us to make a comprehensive analysis of interfacial charge transfer kinetics in PEC system.

Bilayer structured supramolecular light harvesting arrays based on zinc porphyrin coordination polymers for enhanced photocurrent generation in dye sensitized solar cells

Coordination polymers based on an acylhydrazone zinc porphyrin were synthesized and applied in dye sensitized solar cells for enhanced photocurrent generation.

Novel porphyrin-preparation, characterization, and applications in solar energy conversion

Accelerated inner charge transfer in porphyrins promotes a broad light-harvesting ability up to 840 nm and a conversion efficiency of 9.2%.