The primary goal of this investigation is to analyze the influence of the chemical modifications on the electronic structures of N719 derivatives for their use in dye-sensitized solar cells (DSSCs), by employing density functional theory. UV−vis spectra indicate that the electronic configurations are essential to study the absorption of solar irradiation and analyze the charge-transport mechanism between the electron-transport layer (ETL), the electrolyte, and the dye. Open-and closed-shell electronic configurations are related to the absorption and the excitation energies of the dye. According to the results reported here, it is possible to say that the best candidates are N719, N719-2, N719-7, and N719-8 (neutral and dianionic). They may be used as useful dye sensitizers due to their band gap and band alignment with the ETL, which contributes to having an effective charge transport during the functioning of the solar device. Another parameter that is reported in this investigation is the light-harvesting efficiency for all studied systems. This could help to improve the performance of the device, since there is an increment in the generation of charge carriers. These results could be useful as a guide for experimental investigations on chemical modifications of these sensitizers.
The vapor-liquid-solid (VLS) process was applied to fabricate zinc oxide nanowires (ZnO NWs) with a different aspect ratio (AR), morphological, and optical properties. The ZnO NWs were grown on a system that contains a quartz substrate with transparent conductive oxide (TCO) thin film followed by an Al-doped ZnO (AZO) seed layer; both films were grown by magnetron sputtering at room temperature. It was found that the ZnO NWs presented high crystalline quality and vertical orientation from different structural and morphological characterizations. Also, NWs showed a good density distribution of 69 NWs/μm2 with a different AR that offers their capability to be used as possible photoelectrode (anode) in potential future device applications. The samples optical properties were studied using various techniques such as photoluminescence (PL), absorption, and transmittance before and after sensitization with N719 dye. The results demonstrated that NW with 30 nm diameter had the best characteristics as feasible photoelectrode (anode) (high absorption, minimum recombination, high crystallinity). Also, the present samples optical properties were found to be improved due to the existence of N719 dye and Au nanoparticles on the tip of NWs. NWs grown in this work can be used in different photonic and optoelectronic applications.
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