The Design Of Functional Materials, Assembly Of Optical And Electrical Properties Studies

This thesis is composed of two parts. One is the solid-state dye sensitized nanocrystalline solar cell. Another is the chemosensors for metal ions.1. The application of quasi-solid and solid-state electrolytes for dye sensitized nanocrystalline solar cells (DSSCs)The dye-sensitized nanocrystalline solar cell is one of hot spots in the field of materials for photoelectric conversion and nano-technology due to the simple technique and low-cost. However, the challenge still exists how to further improve its stability and energy conversion efficiency in terms of its application. In this study, liquid electrolytes are solidified by introducing mesoporous and organic/inorganic hybrid materials. The main contents and results of this part are reported as following:1. Using the network of the mesoporous SiO₂ (SBA-15) and replacing the organic solvent by ionic liquid to form a quasi-solid electrolyte; which can provide the diffusion path for I^-//I₃^- in the solar cell while deduce the evaporation of the solvent. The liquid electrolyte was composed of 0.3-1.0 M I₂ and 0.45 M 1-methylbenzimidazole in 1-methyl-3-propyl-imidazolium iodine (MPII), and different SBA-15 contents were assembled in DSSCs and were tested for produce stable gel electrolytes. The content of I₂ and SBA-15 were optimized to be 0.5 M I₂ 0.45 M 1-methylbenzimidazole, 3wt% SBA-15 in 1-methyl-3-propyl-imidazolium iodine (MPII) in our experiment conditions. The open-circuit voltage (V_OC), short circuit photocurrent density (J_SC), the fill factor (FF) and overall energy conversion efficiency (7) are found to be 569 mV, 9.1 mA cm^-2, 0.67 and 4.3 %, respectively. The conversion efficiency of the gel electrolyte based solar cell was kept constant, while that of the liquid electrolyte based solar cell decreased to 30% after 700 h, indicating that the introduction of the mesoporous SBA-15 benefited the long term stability of the solar cell.2. Based on the molecular self-assemble theory, the network can be formed by hydrogen bond F…O-H between the tetrafluoroborate group of hydrophilic imidazolium ionic liquid and the hydroxyl group of fumed silica and π—π stack of imidazole rings. The electrolyte composed of 0.18 M I₂, 1.3 M BMI·I, 0.5 M LiI, 1 M 4-tert-butylpyridine and 5wt% SBA-15 in BMI· BF₄ was tested. The optimum results at the room temperature for the DSSC using this electrolyte are 8.0 mA cm^-2 of J_SC, 655 mV of V_OC, 67% of FF, and4.7% of η, More importantly, at the relative high temperature of 60℃, the solar cell based on the it exhibits 5.0% of overall energy conversion efficiency. The efficiency of DSSCs using the liquid electrolyte only kept 30% of their initial efficiency after 1000 h, while no decrease of the efficiency was observed for the solid-state DSSCs.II. Chemosensor for metal cations using the molecules containing urea and thiourea groups as receptorsChemosensors have aroused considerable attention in the filed of ions detecting due to its small size, low cost and accuracy, etc. How to detect heavy metal ions effectively is very important in the fields of biochemistry, environment and medicine. In this part of the thesis, we focused on introducing new receptors into a Naphthalenyl or anthraquinone molecule, such as urea and thiourea groups, and detecting metal ions through the changes of the fluorescence and UV-vis output signal. The main contents and results of this part are listed as following:1. Five Naphthalene derivatives were synthesized for detecting of metal ions by changing donor-acceptor electron groups. The new absorbance band of UV-vis spectra in longer wavelength was found with naphthalene derivatives containing para-donor electron groups when the oxidisability metal ions (such as Fe³⁺, Hg²⁺, Ag⁺, Cu²⁺) were added, while there were not any changes for other metal ions; On the other hand, a red shift fluorescent emission was observed in the presence of Cu (II) for naphthalene derivatives containing no donor-acceptor electron groups or ortho-methoxyl group. Thus it can be seen that the structure and position of the donor acceptor groups are of importance for chemosensors for selectivity of metal ions.2. Three anthraquinone derivatives containing urea group were synthesized by changing donor-acceptor electron groups. The photo-physical characterizations were studied for three anthraquinone derivatives in the absence and presence of different metal ions. The results indicated that anthraquinone derivatives containing para-nitro group could selectively detect Hg (II) by naked eyes. The 60 nm red shift is observed in UV-vis spectra by adding Hg (II). The contrast compound was also synthesized in order to discuss the mechamism.3. Two anthraquinone derivatives containing thiourea group were synthesized. The photo-physical characterizations were studied for two anthraquinone derivatives in theabsence and presence of different metal ions. The results indicated that anthraquinone derivatives could selectively detect Hg (II) and Ag (I) by naked eye. The 58 nm blue shift happened in the presence of Hg (II). The absorbance band at 458 nm decreased and the band centered at 550 nm increased by adding Ag (I). The contrast compounds were also synthesized and ¹HNMR spectra were carried out in order to discuss the mechanism. The different combine site for detecting Hg (II) and Ag (I) was recognized.