Synthesis of Oligo(oxyethylene)-Segmented Polymer and Its Use for Counter Electrodes and Quasi-Solid-State Electrolyte in Dye-Sensitized Solar Cells

This dissertation aims to synthesize a novel polymer dispersant, namely poly(oxyethylene)–segmented imide (POEM), and further applying it as the modifier for preparing the electrocatalysts of counter electrode (CE) and gelatinizing the ionic liquid based electrolyte in dye–sensitized solar cells (DSSCs). The dissertation can be divided into three parts: (1) To enhance the efficiency of DSSC, novel polymer POEM was introduced and served as the dispersant for synthesizing the platinum (Pt)/multi–wall carbon nanotubes (MWCNTs) composite to faciliate the charge transport of CE in DSSCs (Chap. 3); (2) In order to further improve the cell performance and reduce the cost of DSSCs, novel polymer POEM was served as the surfactant to control the particle size and shape of Pt nanostructure particles and conducting polymer nanoparticle, which were applied as the catalyst materials in CE of DSSCs (Chap. 4, 5). (3) To improve the stability of the DSSCs, novel polymer POEM was used as the gelatinizing agent to solidify the room temperature ionic liquids (RTILs) electrolyte for preparing a new polymer–gelled ionic liquid electrolyte for quasi–solid–state DSSC (QSS-DSSC). (Chap. 6).
In general, Pt is the most commonly used catalytic material on the CE because of its excellent catalytic ability and stability in the system with iodide/triiodide (I–/ I3–) electrolyte. However, the expensive Pt leads to a high cost for the fabrication of DSSCs. To solve this problem, the concept of composite materials was proposed to reduce the usage of Pt at the first part in this dissertation. To enhance the efficiency of DSSC, novel polymer POEM was introduced and served as dispersant for synthesizing the well–dispersed PtNPs/MWCNTs composite owing to its amide group at the end of polymer chain. In this part, a cell efficiency of 9.04% can be achieved with a DSSC containing the PtNPs/MWCNTs composite film on the Ti foil flexible substrate, compared to that of the DSSC with Pt CEs (