Multi-functionality of macroporous TiO2 spheres in dye-sensitized and hybrid heterojunction solar cells

Prickly pear fruit extract as photosensitizer for dye-sensitized solar cell

In this study, we have explored prickly pear fruit extract as a photosensitizer in dye-sensitized solar cells (DSSC). The photosensitizer was isolated from prickly pear fruits by extraction method using ethanol as solvent. Structural, morphological and optical properties of prickly pear extract characterized by XRD, SEM, UV-VIS-DRS, FTIR spectra, respectively. UV-VIS absorption and FTIR spectra of prickly pear fruit extract confirm the presence of betacyanin and hydroxyl groups anchoring onto the TiO₂ surface. The absorption maxima at 534 nm in the visible region is prominent. The presence of betacyanin in the extract is indicative that the dye will be useful as a sensitizer in DSSC. Reflectance edge of TiO₂ is red-shifted upon the adsorption of natural dye. The XPS analysis showed the charge state of hydroxyl (O-H) groups that are attached with the natural dye adsorbed onto the surface of TiO₂. The fabricated DSSC had a conversion efficiency (ɳ) of 0.56% with highest fill factor (FF) of 0.85, open-circuit voltage (V_oc) of 0.56 V and short circuit-current density (J_sc) with 1.17 mA/cm². The value obtained for the fill factor is promising to further explore the prickly pear extract for applicability in DSSC by improving the efficiency.

Monolithic Two-Dimensional Photonic Crystal Reflectors for the Fabrication of Highly Efficient and Highly Transparent Dye-Sensitized Solar Cells

The transparent characteristic of dye-sensitized solar cells (DSCs) makes them suitable for building integrated photovoltaic (BIPV) devices. However, the diffusive scattering layer, which is usually used to increase the efficiency of these devices, greatly lowers the transparency of the DSC. This paper described a two-dimensional (2D) photonic crystal (PC) reflector with a sub-micrometer characteristic length that can improve the efficiency of these devices while maintaining transparency. This 2D PCs were fabricated directly onto TiO₂ photoelectrodes using colloidal lithography and have the structure of a nanopillar array. A nanopillar with a height of 430 nm was observed to selectively reflect up to 40% of the light of 400-500 nm wavelength. The perceived transparency of the 2D PC electrode was 52%, which is much higher than 0.3% of the conventional scattering layer. The DSC fabricated using the 2D PC electrode demonstrated a maximum photon-to-electric conversion efficiency of 8.23%, which is 18% higher than the pristine electrode. The 2D PC is a highly efficient and wavelength-selective reflector that can be applied to various photoelectric conversion devices.

Self-Position of Au NPs in Perovskite Solar Cells: Optical and Electrical Contribution

Metallic nanoparticles (NPs) exhibit a localized surface plasmon resonance (LSPR) and act as scattering centers and subwavelength antennas, so metallic NPs can be incorporated into perovskite solar cells (PSCs) to effectively improve the light absorption of light harvesting devices. Here, we have embedded Au nanoparticles (NPs) into the hole transport layer (HTL) of the PSCs to investigate the photovoltaic effect of the PSCs with Au NPs. Interestingly, it was found that Au NPs dispersed spiro-OMeTAD HTL solution could naturally end up located near the perovskite layer as the result of the spin-coating step. Solar cell performance observations indicate that the LSPR and electrical effects of Au NPs enhance the photovoltaic response of PSCs, in spite of a slight decrease in the open-circuit voltage (VOC), by causing an incredible improvement in the photocurrent density as a dominant factor.

Synthesis and applications of porous non-silica metal oxide submicrospheres

A variety of metal oxide particles of spherical morphology from nano to micrometer size have been reviewed with a special emphasis on the appraisal of synthetic strategies and applications in biomedical, environmental and energy-related areas.

Hierarchical TiO2–B/anatase core/shell nanowire arrays for efficient dye-sensitized solar cells

Hierarchical TiO₂–B/anatase core/shell heterojunction nanowire arrays on a titanium plate substrate are synthesized and used as novel photoanode materials for DSSCs.

Two Ti13-oxo-clusters showing non-compact structures, film electrode preparation and photocurrent properties

Photoelectrodes are prepared by a wet coating process using solutions of two new Ti₁₃ clusters that possess non-compact structures and the photocurrent response properties of the electrodes are studied.