RESUMEN
Photovoltaic generation has stepped up within the last decade from outsider status to one of the important contributors of the ongoing energy transition, with about 1.7% of world electricity provided by solar cells. Progress in materials and production processes has played an important part in this development. Yet, there are many challenges before photovoltaics could provide clean, abundant, and cheap energy. Here, we review this research direction, with a focus on the results obtained within a Japan-French cooperation program, NextPV, working on promising solar cell technologies. The cooperation was focused on efficient photovoltaic devices, such as multijunction, ultrathin, intermediate band, and hot-carrier solar cells, and on printable solar cell materials such as colloidal quantum dots.
RESUMEN
Plasmonic core-shell Au@SiO2 nanoparticles have previously been shown to enhance the performance of dye-sensitized solar cells (DSSCs). A thin silica coating can provide a better stability during thermal processing and chemical stability to survive the corrosive electrolyte used in DSSCs. However, the thickness and completeness of the silica shell has proven crucial for the performance of the plasmonic particles and is largely controlled by the linking chemistry between the gold core and silica shell. We have evaluated four different silica coating procedures of â¼15 nm gold nanoparticles for usage in DSSCs. The chemical stability of these core-shell nanoparticles was assessed by dispersing the particles in iodide/triiodide electrolyte solution and the thermal stability by heating the particles up to 500°C. In order to maintain stable gold cores a complete silica coating was required, which was best obtained by using a mercaptosilane as a linker. In situ TEM characterization indicated that the heating process only had minor effects on the core-shell particles. The final step was to evaluate how the stable Au@SiO2 nanoparticles were influencing a real DSSC device when mixed into the TiO2 photoanode. The plasmon-incorporated DSSCs showed a â¼10% increase in efficiency compared to devices without core-shell nanoparticles.
RESUMEN
Toward the extension of the light-harvesting region of sensitizers in dye-sensitized solar cells (DSSCs), two ethynyl-linked porphyrin trimers were synthesized and investigated. The zincfreebasezinc trimer (ZnFbAZn) showed an absorption maximum at a longer wavelength than the all-zinc trimer (ZnZnAZn), although the energy level of ZnFbAZn was lower than that of ZnZnAZn. The DSSCs using these trimers showed spectral sensitivities up to 900 nm. Reflecting the energy levels of these trimers, the DSSC using ZnZnAZn showed better performance than that using ZnFbAZn. After the optimization of cell fabrication conditions, the photoelectric conversion efficiency η of the DSSC using ZnZnAZn reached 3.17%. The larger TiO2 nanoparticles (ca. 37 nm) than the conventional cases (ca. 13 nm) were found to be preferable in this case, due to high molar extinction coefficients of the porphyrin trimers.
