| As a typical third-generation photovoltaic device, dye-sensitized solar cell (DSC), has been regarded as one of the most promising solar cells due to their simple procedure, low-cost and environment-benign feature. With the joint efforts of worldwide researchers over the past twenty years, the power conversion efficiency (PCE) of13.0%for DSC has been achieved. However, the industrialization of DSC is still restricted due to the poor stability and high cost. To solve such drawbacks, this thesis will focus on improving the long-term stability and reducing the production cost of DSC, developing novel high-efficient and high-stable electrolyte systems and low-cost nanomaterials for counter electrodes (CEs), as well as the effects of developed electrolytes/CEs on the performance of DSCs. Furthermore, the important correlations of catalytic activities of different CEs for redox couples were also investigated in detail. In addition, a novel all-natural DSC device was fabricated with all the key components derived from biomass material-sea tangle (ST).Firstly, three high-efficient and high-stable electrolyte systems were designed and developed:(1) Polyvinyl acetate (PVAc) synthesized via a solution polymerization method, was used for preparing quasi-solid state electrolyte and subsequently applied for DSC. The results showed that the quasi-solid state electrolyte exhibits the comparable PCE to liquid electrolyte and excellent stabilities;(2) A series of novel BOB ionic liquids (ILBOBs) were explored as additives of liquid electrolyte with organic solvent, and a high PCE of8.73%was achieved. Systematic investigations were carried out to reveal the underlying mechanism of ionic liquid structures on affecting the performances of DSCs. In addition, the PCE could be dramatically improved by54.6%and a superior long-term stability could also be acquired when introducing ILBOBs into pure ionic liquid electrolyte systems;(3) We developed a novel I2-free electrolyte system based on â… -/â… 2-, and verified its feasibility via electrochemistry methods. Effects of concentration, solvents, the thickness of photoanode and spacer on the performance of DSCs have been thoroughly investigated for possible optimization in performance. The corresponding PCE of8.82%, similar to the value of traditional electrolyte, was achieved. The universality of the developed â… 2-free electrolyte was also corroborated in the study.Secondly, three hierarchical flower-like iron oxides, α-Fe2O3, γ-Fe2O3and Fe3O4, were synthesized by hydrothermal method and applied as CEs for DSC. The fundamental influence of morphologies and crystal phases of such iron oxides on DSC performances was investigated systematically. Among them, Fe3O4showed the best photovoltaic performance. Upon further optimization, the highest PCE of7.80%was obtained, which is close to the value of DSC assembled with sputtered Pt. Moreover, the C/Fe3O4composite catalytic materials, derived from biomass materials-rosin, were fabricated as CEs for DSC. The results suggested that the composite material shows better conductivity and catalytic activity than their mono-components, and achieves higher PCE of8.11%.Thirdly, the essential materials of dye, electrolyte and CE for DSC, derived from biomass materials-ST, were developed. The prepared ST carbon CE showed similar PCE (7.82%) to that of sputtered Pt. Based on the unique feature of the biomass template of ST, ST carbon/Fe304composite was prepared at low temperature and applied for DSC. The improvement of the PCE up to24.2%was gained compared with the value before composition. Consequently, the constructed all-natural DSC achieved a high PCE.Finally, the catalytic mechanisms of the catalytic materials of CEs for organic redox couples (e.g., T-/T2and Co2+/Co3+) were investigated systematically by multiple electrochemistry methods. Several non-Pt materials (e.g., OMC-WC, WC, TiC, NbO2) were found to exhibit better catalytic activities and markedly augmented PCEs than Pt. |
