Mesoporous films prepared from synthesized TiO2 nanoparticles and their application in dye-sensitized solar cells (DSSCs)

Double anchor indolo[3,2-b]indole-derived metal-free dyes with extra electron donors as efficient sensitizers for dye-sensitized solar cells

New di-acceptors organic dye with extra electron donors shows an enhanced PCE of 7.86% comparing to parent one.

An all carbon dye sensitized solar cell: A sustainable and low-cost design for metal free wearable solar cell devices

Lightweight carbon electrodes are the new candidates for photovoltaic devices due to their temperature resistivity, ease of fabrication, and skin comfortability. Herein, a sustainable and facile strategy has been proposed for metal free all carbon dye sensitized solar cell (C-DSSC), assembled by stacking carbon front electrode (CFE) and carbon counter electrode (CCE). The CFE demonstrated adequate light transmittance (70-50%) while maintaining efficient photon absorption and charge separation mechanism due to dye coated TiO₂ nanorods (P25-R). The graphene dip coated carbon counter electrode (Gr@CCE) possesses remarkable electro catalytic activity towards I₃^-/I^- redox couple with low charge transfer resistance (R_CT = 0.79 Ω). The sustainable design of C-DSSC attained ~6 ± 0.5% efficiency with high photocurrent density of 18.835 mA. cm^-2. The superior performance of C-DSSC is accredited to its improved charge mobility, low internal resistance, and better interfacial electrode contact. The thickness of C-DSSC is ≤3 mm eliminates the need for rigid glass in DSSC.

Influence of the electron donor properties of hypericin on its sensitizing ability in DSSCs

Rising demands for renewable energy sources have led to the development of dye sensitized solar cells. It is a challenge to find a good and low cost sensitizer, which has a low environmental impact. In this work, we conducted spectroscopic and electrochemical experiments, as well as quantum-chemical calculations of the natural pigment hypericin, in order to provide insight into its sensitizing efficiency. To this end, three identical cells were made and characterized. Although this pigment exhibited good adsorption onto a semiconductor surface, a high molar absorption coefficient (43 700 L mol^-1 cm^-1) and favorable alignment of energy levels and provided a long lifetime of electrons (17.8 ms) in the TiO₂ photoanode, it was found that the efficiency of hypericin-sensitized solar cells was very low, only 0.0245%. We suggest that this inefficiency originated from a low injection of electrons into the conduction band of TiO_2. This conclusion is supported by the density functional theory calculations which revealed a low electron density in the anchoring groups of electronically excited hypericin. The results of this work could be valuable not only in the photovoltaic aspect, but also for application of hypericin in medicine in photodynamic therapy.

Synthesis and characterization of two new TiO2-containing benzothiazole-based imine composites for organic device applications

The effect of the presence of titanium dioxide in two new imines, (E,E)-(butane-1,4-diyl)bis(oxybutane-4,1-diyl) bis(4-{[(benzo[d][1,3]thiazol-2-yl)methylidene]amino}benzoate) (SP1) and (E)-N-[(benzo[d][1,3]thiazol-2-yl)methylidene]-4-dodecylaniline (SP2), on the properties and stability of imine:TiO₂ composites for organic device applications were examined. The investigated titanium dioxide (in anatase form, obtained via the sol-gel method) exhibited a surface area of 59.5 m²/g according to Brunauer-Emmett-Teller theory, and its structure is a combination of both meso- and microporous. The average pore diameter calculated by the Barrett-Joyner-Halenda method was 6.2 nm and the cumulative volume of pores was 0.117 m³/g. The imine SP1 exhibited columnar organization (Col), while SP2 revealed a hexagonal columnar crystalline phase (Col_hk). The imine:TiO₂ mixtures in various weight ratio (3:0, 3:1, 3:2, 3:3) showed a lower energy gap and HOMO-LUMO energy levels compared to pure TiO₂. This implies that TiO₂ provides not only a larger surface area for sensitizer adsorption and good electron collection, but also causes a shift of the imine energy levels resulting from intermolecular interaction. Also the temperature of the phase transition was slightly affected with the increase of TiO₂ concentration in imine-based composites. The changes observed in the Fourier transform middle-infrared absorption (FT-MIR) spectra confirmed the significant influence of TiO₂ on structural properties of both investigated imines. Similar interactions of oxygen vacancies existing on the TiO₂ surface with SP1 and SP2 were observed. The imine:TiO₂ mixtures showed good air stability and reusability, which demonstrates its potential for organic device applications.