Synthesis And Photovoltaic Properties Of Novel Benzo[a]Carbazole-Substituted Porphyrin And Phenothiazine Photosensitizers

In the 21 st, the problems of energy and environment have become the urgent issues in modern society. Developing and utilizing the new type of clean and renewable energy resources is the silly port of solving the issues of energy, environment, and human sustainable deve lopment. As one of the popular research fields, dye-sensitized solar cells(DSSCs) have been extensively investigated due to their facial fabrication processes, environment friendly, and low cost. Photosensitizers play a vital role in DSSCs, the optical-electrical characteristics of which can be tuned through different decorations and structural modifications. As we all know, organic sensitizers have relatively wide absorption spectrum, high molar extinction coefficient, low cost, facial syntheses, and easy decoration, which provide the possibility of large-scale development and utilization of organic photosensitizers.Donor�?- linker�acceptor(D�?�A) type structure is an ordinary type of photosensitizers and exhibits high power conversion efficiency. These D�?�A type of organic dyes have highly efficient intramolecular charge transfer(IC T) and good potential to achieve high power conversion efficiency(PCE). The electron-rich ?-bridge is often preferable to promote the ICT process and expand the spectral response range. In this work, two types of porphyrin and metal- free sensitizes, have been successfully synthesized and applied in dye-sensitized solar cel s.Firstly, four porphyrin sensitizers(GHH01�04) have been designed and synthesized to investigate the effect of the introduction of phenyl, 4-ethynylphenyl, benzothiadiazole(BTD) as the ?-conjugated linkers and the introduction of ethynyl in donor group. It has been discovered that via prolonging the length of conjugated system, the absorption range in visible region of the sensitizers will be expanded, and the short-current density of the sensitizer would be improved. Among these dyes, GHH06 achieved the best power conversion efficiency(6.69%) and a photovolatic conversion efficiency(PCE) of 8.41% have achieved when co-sensitized with JY23.Secendly, three novel oligothiophene- linked D�?�A type phenothiazine dyes have been designed and synthesized(GHH05�07). In this section, this type dyes consist of a phenothiazine as the donor group, oligothiophene as the ?-bridge, and a 2-cyanoacylic acid as the acceptor.We have systematically researched the effects of long alkyl chains and secondary donor groups on the photoelectric properties of these dye molecules. It has been discovered that the introduction of two n-octyl on oligothiophene ?-bridge significantly impeded the dye-aggregation on the surface of titanium dioxide film and improved the open-circuit voltage of the resultant device. At the meantime, the introduction of secondary donor group 4-butoxyphenyl on phenothiazine dramatically improved the short-circuit current density, and finally improved the power conversion efficiency. Among these dyes, GHH07 achieved the highest power conversion efficiency(7.48%).