Design And Synthesis Of New Organic Optoelectronic Materials And Their Applications

Organic solar cells have attracted much attention in the field of solar cells due to their advantages such as low cost,facile preparation and high charge carrier mobility.In recent years,researchers around the world are committed to improving the conversion efficiency of organic solar cells.After many years of development,the highest efficiency of small molecule/polymer solar cells has reached over 11%,and the efficiency of n-type dyesensitized solar cells has been exceeding 13% in lab.However,compared to the inorganic solar cells,the efficiency is not high,and there is still much room for the improvement of organic solar cells.Organic materials play an important role in solar cells.Rational design of organic materials could effectively increase the light harvesting ability,improve charge separation efficiency,reduce charge recombination and then improve the photoelectric conversion efficiency.Therefore,it is necessary to design reasonable organic materials to improve the efficiency of organic solar cells.In this thesis,new organic solar cell materials were designed and synthesized.At the same time,their photovoltaic properties were investigated.The main contents include the following three parts:1.Three triphenylamine-based dyes?Q1,Q2 and Q3?were designed and synthesized,and the effect of dye structure on dye-sensitized solar cells was also systematically investigated through the device characterization.Results showed that the introduction of 5-heptylthiophene and hexyloxy groups could effectively avoid the charge recombination and increase the charge mobility.In addition,we find that the post-treatment of TiCl4 on TiO2 is not always able to improve the photoelectric conversion efficiency of DSSCs.In Q1,there is only one 5-hexylthiophene substitution on the TPA structure,while in Q2,there are one 5-hexylthiophene group and one hexyloxy.After TiCl4 treatment,the efficiency of solar cells based on Q1 and Q2 have been improved.However,the efficiency of Q3 with two thiophene group has no remarkable enhance.2.A new near-infrared molecule based on symmetry squaraine?TPE-SQ?was designed and synthesized,and was applied to ternary organic solar cells.Results showed that TPE-SQ exhibited good solubility and absorption ability with a sharp and strong absorption band in the near-infrared region?600⁷50 nm?.And its absorption in the film state is also very wide,ranging from 550 to 900 nm.The devices fabricated by doping TPE-SQ into P3 HT mixed with the PC₇₁ BM were achieved.We found that the absorption range of ternary organic solar cells was widened by introducing a third component TPESQ.Results showed that a small amount of TPE-SQ can effectively improve the photoelectric conversion efficiency of organic solar cells.After the doping of TPE-SQ,the photoelectric conversion efficiency of ternary solar cell was up to 3.93%,which corresponds to about 20% increase compared to the binary system.3.As a typical squaraine molecule,TPE-SQ can be easily attacked by nucleophiles like thiols because its core structure is an electron deficient unit.When attacked by thiols,the whole conjugate structure of TPE-SQ is destroyed,resulting in a color change of solution,as well as in fluorescence emission change.Through UV-Vis absorption and fluorescence emission spectra,we investigated the detection property of TPE-SQ towards thiols,including cysteine?Cys?,glutathione?GSH?and homocysteine?Hcy?.It turned out that TPE-SQ showed good selectivity and high sensitivity for the detection of thiols,with detection limits of 9.8 nM for Cys,12.4 nM for GSH and 9.7 nM for Hcy,respectively.Therefore,TPE-SQ can be used as a ratiometric fluorescent probe for the detection of thiols.