Screen printed Pb₃O₄ films and their application to photoresponsive and photoelectrochemical devices

A new and simple procedure for the deposition of lead (II, IV) oxide films by screen printing was developed. In contrast to conventional electrochemical methods, films can be also deposited on non-conductive substrates without any specific dimensional restriction, being the only requirement the thermal stability of the substrate in air up to 500 °C to allow for the calcination of the screen printing paste and sintering of the film. In this study, films were exploited for the preparation of both photoresponsive devices and photoelectrochemical cell photoanodes. In both cases, screen printing was performed on FTO (Fluorine-Tin Oxide glass) substrates. The photoresponsive devices were tested with I-V curves in dark and under simulated solar light with different irradiation levels. Responses were evaluated at different voltage biases and under light pulses of different durations. Photoelectrochemical cells were tested by current density⁻voltage (J-V) curves under air mass (AM) 1.5 G illumination, incident photon-to-current efficiency (IPCE) measurements, and electrochemical impedance spectroscopy

Digital imaging to simultaneously study device lifetimes of multiple dye-sensitized solar cells

In situ degradation of multiple dyes (D35, N719, SQ1 and SQ2) has been investigated simultaneously using digital imaging and colour analysis. The approach has been used to study the air stability of N719 and squaraine dyes adsorbed onto TiO2 films with the data suggesting this method could be used as a rapid screening technique for DSC dyes and other solar cell components. Full DSC devices have then been tested using either D35 or N719 dyes and these data have been correlated with UV-vis, IR and XPS spectroscopy, mass spectrometry, TLC and DSC device performance. Using this method, up to 21 samples have been tested simultaneously ensuring consistent sample exposure. Liquid electrolyte DSC devices have been tested under light soaking including the first report of D35 testing with I�/I3 � electrolyte whilst operating at open circuit, short circuit, or under load, with the slowest degradation shown at open circuit. D35 lifetime data suggest that this dye degrades after ca. 370 h light soaking regardless of UV filtering. Control, N719 devices have also been light soaked for 2500 h to verify the imaging method and the N719 device data confirm that UV filtration is essential to protect the dye and I3 �/I� electrolyte redox couple to maintain device lifetime. The data show a direct link between the colour intensity and/or hue of device sub-components and device degradation, enabling “real time” diagnosis of device failure mechanisms

Optical and Chemical Properties of Fragaria ananassa and Galena: Potential Photosensitizers in a Natural Dye-Sensitized Solar Cell

Dye is one of the major components for high power conversion efficiency in a dye-sensitized solar cell. There are challenges natural dyes encounter, especially with quick degradation of the dye molecules. This work considered mineral dye in comparison with plant dye to address the challenge of degradation of natural plant dyes. The optical properties and functional groups of the two natural dyes were studied in this work. The absorption spectra, the optical band gaps and the absorption coefficients of the dyes were reported and found to be suitable for use as photosensitizers in a dye-sensitized solar cell (DSSC), as they absorb in the visible region of the electromagnetic radiation. The functional groups were studied by carrying out Fourier transform infrared spectroscopy and the amine, carbonyl and hydroxyl groups present in both dyes confirmed promising material that can absorb solar radiation in the visible region (around 380–800 nm) and which finds application in fabricating DSSC. The organic compositions in the mineral dye are studied via the gas chromatography-mass spectrometry and the results justify the observation from the FTIR spectroscopy. The properties observed, via the characterizations techniques used, confirm materials suitable for use as photosensitizers in fabricating DSSC. Keywords: Plant dye, Mineral dye, Photosensitizer, Visible region, DSSC

PELAPISAN NANOPARTIKEL DAN NANOFIBER TITANIUM DIOXIDE (TiO2) DI ATAS FLUORINE-DOPED TIN OXIDE (FTO) UNTUK APLIKASI DYE-SENSITIZED SOLAR CELL (DSSC)

Nanofiber TiO2 telah berhasil dibuat dari material Titanium (IV) Isopropoxide (TTIP), Acetic Acid, Ethanol, dan Polivynil Pyrolidone (PVP) menggunakan electrospinning. Lapisan nanofiber dibuat di atas lapisan nanopartikel yang dideposisi dengan menggunakan spin coating. Lapisan nanofiber dibuat dengan variasi waktu pelapisan yaitu 10 menit, 15 menit dan 20 menit dengan suhu annealing yang sama yaitu 450°C selama 3 jam. Fase nanofiber TiO2 dikarakterisasi menggunakan X-Ray Diffraction (XRD) dan morfologi nanofiber TiO2 diamati menggunakan Atomic Force Microscopy (AFM). Efisiensi Dye Sensitized Solar Cell (DSSC) dapat diperoleh dari kurva arus-tegangan I-V meter. Pola difraksi XRD nanofiber TiO2 menunjukkan semua puncak adalah fase anatase. Nanofiber TiO2 mempunyai diameter rata-rata 781 nm. Nanofiber TiO2 pada waktu pelapisan 15 menit tersebar merata di atas FTO dibanding dengan waktu pelapisan 10 menit dan 20 menit. Sehingga waktu pelapisan 15 menit dipilih untuk aplikasi DSSC dengan β-carotene wortel sebagai dye, larutan I3-/I- sebagai elektrolit dan lapisan karbon sebagai katalis. Pelapisan nanofiber di atas lapisan nanopartikel dapat meningkatkan efisiensi DSSC sekitar 20% dibandingkan dengan hanya lapisan nanopartikel saja. Hal ini diperkirakan bahwa nanofiber berfungsi dominan sebagai penjebak foton sedang nanopartikel berfungsi dominan sebagai penyerap dye sehingga interaksi antara foton dan dye semakin banyak. Interaksi foton dan dye menghasilkan elektron. Banyaknya elektron yang dihasilkan dapat meningkatkan efisiensi

Morphological Effect of CNT/Ti O

This research focused on the fabrication of dye-sensitized solar cell based on a photoanode of carbon nanotube/titanium dioxide (CNT/TiO2) nanocomposite photoanode synthesized through acid-catalyzed sol-gel method. The results show the improvement of the chemical and electrical properties of the solar cells annealed at different temperatures. The CNT/TiO2 colloidal solution was synthesized using titanium tetraisopropoxide and CNT/2-propanol solution. The thin films were doctor-bladed on a fluorine tin oxide glass before being annealed at 550, 650, and 750°C. The field emission scanning electron microscopy morphological images show that the thin films were homogenously distributed and maintained their spherical structures. The X-ray diffraction patterns show that the films consisted of anatase and rutile phases with large crystallite sizes due to temperature increment. The atomic force microscopy analysis presents the thin film roughness in terms of root mean square roughness. The photovoltaic performance was analyzed using IV curve and electrochemical impedance spectroscopy (EIS). The thin films annealed at 750°C had the highest energy conversion efficiency at 5.23%. The EIS analysis estimated the values of the effective electron lifetime (τeff), effective electron diffusion coefficient, effective electron diffusion (Ln), and effective recombination rate constant (keff). A large τeff, small keff, and longer Ln can improve photovoltaic performance efficiency

Solvent Effects on Dye Sensitizers Derived from Anthocyanidins for Applications in Photocatalysis

Anthocyanidins under the effects of solvents water, ethanol, n-hexane, and methanol are interesting due to their suitability as natural dyes for photocatalytic applications. In this chapter, DFT and TDDFT methodologies are used to study their electronic structure. The results displayed include HOMO, LUMO, HOMO-LUMO gap, chemical properties, and reorganization energies for the ground states, and excited state data are also displayed. Malvidin in gas phase has lower gap energy. After addition of solvents, gap energy increases in all cases but malvidin with n-hexane presents narrower gap. Conceptual DFT results show that cyanidin and malvidin may have good charge transfer. Cyanidin presented lower electron reorganization energy (λe) using solvent water; however, ethanol and methanol had similar values. TDDFT is used to calculate excited states, and absorption data show wavelength main peak between 479.1 and 536.4 nm. UV-Vis absorption spectra were generated and solvent effects on each molecule is discussed. Anthocyanidins work well in the visible region with the stronger peak at the green region. These pigments are good options for photocatalysis application and cyanidin and malvidin, in this order, may be the best choices for dye sensitization applications

Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells?

The syntheses of 4,40 -bis(4-dimethylaminophenyl)-6,60 -dimethyl-2,20 -bipyridine (1 ), 4,40 -bis(4-dimethylaminophenylethynyl)-6,60 -dimethyl-2,20 -bipyridine (2 ), 4,40 -bis(4- diphenylaminophenyl)-6,60 -dimethyl-2,20 -bipyridine (3 ), and 4,40 -bis(4-diphenylaminophenylethynyl)- 6,60 -dimethyl-2,20 -bipyridine (4 ) are reported along with the preparations and characterisations of their homoleptic copper(I) complexes [CuL2 ][PF6 ] (L = 1 -4 ). The solution absorption spectra of the complexes exhibit ligand-centred absorptions in addition to absorptions in the visible region assigned to a combination of intra-ligand and metal-to-ligand charge-transfer. Heteroleptic [Cu(5 )(Lancillary )]+ dyes in which 5 is the anchoring ligand ((6,60 -dimethyl-[2,20 -bipyridine]- 4,40 -diyl)bis(4,1-phenylene))bis(phosphonic acid) and Lancillary = 1 -4 have been assembled on fluorine-doped tin oxide (FTO)-TiO2 electrodes in dye-sensitized solar cells (DSCs). Performance parameters and external quantum e ciency (EQE) spectra of the DSCs (four fully-masked cells for each dye) reveal that the best performing dyes are [Cu(5 )(1 )]+ and [Cu(5 )(3 )]+ . The alkynyl spacers are not beneficial, leading to a decrease in the short-circuit current density (JSC ), confirmed by lower values of EQEmax . Addition of a co-absorbent (n -decylphosphonic acid) to [Cu(5 )(1 )]+ lead to no significant enhancement of performance for DSCs sensitized with [Cu(5 )(1 )]+ . Electrochemical impedance spectroscopy (EIS) has been used to investigate the interfaces in DSCs; the analysis shows that more favourable electron injection into TiO2 is observed for sensitizers without the alkynyl spacer and confirms higher JSC values for [Cu(5 )(1 )]