Preparation And Study On Polymer Photovoltaic Devices And Flexible Counter Electrode For Dye-sensitized Solar Cells

In this dissertation, the research progress in bulk-heterojunction polymer solar cell (PSCs) and the counter electrode (CE) for dye-sensitized solar cells (DSSCs) were introduced systematically. The interphase morphology of the donor and acceptor is a vital ingredient to affect the power conversion efficiency (PCE) of bulk-heterojunction polymer solar cells. In this study, the relationship between the interphase morphology of photovoltaic active layer based on a phenyleneviny-alt-trithiophene copolymer and the photovoltaic performance was studied, and a high performance PSCs device based on double donors was fabricated. As one of the indispensable components in DSSCs, CE should be low cost and high performance. However, platinum CE is not an economic way for mass production. In the study, high peformance flexible carbon aerogel CE was prepared as a low cost substitute for platinum counter electrode. The main study results are as follows:1. PSCs devices were fabricated and optimized with a phenyleneviny-alt-trithiophene copolymer as electron donor, and PCBM as electron acceptor. The microphase separation of the photovoltaic active layer with different weigh ratio of donor and acceptor was discussed. Two conjugated polymers with electron-withdrawing side chain and electron-donating side chain were blended in the photovoltaic active layer as electron donor materials to improve exciton life time and exciton diffusion length. The result indicated that the PCE of the PSCs devices based on P2 and P3 was 1.75% and 1.49%, respectively. Whereas, the PCE of PSC device with double donors reached 1.97% without any annealed procedure.2. High efficiency DSSCs were fabricated with carbon aerogel, carbon black and active carbon CEs on flexible stainless steel mesh, and the electrocatalytic activity of these flexible carbon CEs was investigated. The photophysical and photochemical were investigated by scanning electron photomicrograph, BET specific surface area, pore size distribution, electrochemical impedance and photovoltaic properties in detail. The results indicate that catalytic reduction activity of carbon aerogel with high specific surface area is superior to carbon black and graphite. Though the SBET of active carbon is twice larger than that of carbon aerogel, the cell with the carbon aerogel CE shows higher short-circuit photocurrent and conversion efficiency. It indicates that the mesopore structure and the large mesopore volume of carbon aerogel facilitate the diffusion of I₃^- ions at the interface of electrolyte and the CE. In the same conditions, the PCE of the DSSC based on Pt CE reached 9.14% and Voc was 0.74V. However, that based on carbon aerogel reached 9.43%, and Voc was 0.84V. It suggests that flexible carbon aerogel CE has strong potential for high performance DSSCs.