Preparation And Photoelectric Properties Of Triphenylamine Pure Organic Dye Sensitizers

With the boom of the global economy, energy shortages have become an urgent problem for each country. The traditional non-renewable fossil energy, such as petroleum, coal and natural gas, is on the decrease. An increasing number of countries turn to pay attention to development and utilization of renewable energy sources. Solar energy is becoming a prodigious concern due to its merits of clean and green, bottomless reserves and low cost, the development modes of solar energy are as follows:solar-thermal conversion, photovoltaic conversion, photochemical conversion and solar-biological transformation, and the most efficient way is photovoltaic conversion, which converts solar energy into electric energy by the path of solar cell. Among the solar cells, dye-sensitized solar cell (DSSC) has aroused widespread concern due to its numerous advantages, such as high efficiency, low cost and low pollution. In 1991, a Swiss scientist named Gratzel published a study about ruthenium complex dye of the dye-sensitized solar cell in Nature with a photoelectric conversion efficiency (PC E, ?) of 7.9%, which initiated a prelude of DSSC research boom Currently, the highest photoelectric conversion efficiency of DSSC has reached to 13%. Generally, DSSC consists of photo anode, counter electrode, electrolyte and dye sensitizers. Dye sensitizers are mainly divided into two parts:metal organic complex dye sensitizers and organic dye sensitizers. Normally, organic dyes feature a structure of electron donor-? bridge-electron acceptor (D-?-A). To further improve the performance of DSSC devices, a series of research on organic dye sensitizers has been carried out. The main study works focus on the following three aspects:1. A couple of (D)2-D-?-A dye sensitizers DD3A and DD4A based on triphenylamine-benzil was designed and fabricated. Compared to the typical D-?-A dyes, DD3 A and DD4A introduce a pair of auxiliary electron donor with strong electron-donating ability on the electron donor, enhancing the electron-dona ting ability of the dye, improving the open-circuit voltage and short circuit current of the DSSC devices and finally increasing the photoelectric conversion efficiency of the DSSC. When the DD3A and DD4A dyes are applied to the DSSC, the DD4A-based DSSC shows the highest photoelectric conversion efficiency of 3.89%.2. In order to improve the electron transfer ability of dye sensitizers, we introduce an auxiliary electron donating group into D-?-A dye, which enhances the electron donating ability of dyes. Moreover, double electron acceptors are introduced into D-?-A dye to enhance dye electron accepting ability. Triphenylamine-benzil based D-D-?-(A)2 type dye sensitizers DD3 and DD4 are designed, fabricated and applied to DSSC. The corresponding devices lead to well-deserved performance, and the DD4-based DSSC shows the highest photoelectric conversion efficiency of 3.33%.3. Co-sensitization can dramatically enhance the performance of DSSC by broadening the absorbance range of sensitizer. In this paper, DD4 and N719 are mixed in certain molar ratio and applied into DSSC, when the molar ratio comes to 2:8, the co-sensitizer shows the highest performance of 8.69%, which is 5% higher than the individual N719 sensitizer.4. Tetrathiafulvalene (TTF) and derivatives is becoming an important functional unit of photoelectric materials research due to marvelous reversible redox properties and strong electron donating ability. In this paper, TTF and its derivative dithiafulvenyl (DTF) are introduced into triphenylamine based D-n-A dye sensitizers separately to synthesize dye sensitizers DDO and DD1, intending to enhance the electron transport capability, stability of the molecules, molar extinction coefficient and ultimately enhance the photoelectric conversion efficiency of DSSC. Applying this two dye sensitizers to DSSC devices, photoelectric conversion efficiency of DDO-based DSSC is of up to 2.77%, higher than that of DD1-based DSSC. It's evident that TTF and DTF show an outstanding electron donating ability and a cheerful prospect in photovoltaic field despite the improvement in PCE is not particularly massive.5. The solvent exert tremendous influence on the PCE of DSSC arises from the diversity of polarity and solubility. In this paper, ethanol, tetrahydrofuran and dichloromethane are respectively utilized to prepare sensitizer solution and applied into DSSC, and the final PCE is 2.77%,2.29% and 1.31%, demonstrating that high-polarity solvent can promote the PCE of DSSC and poor-solubility solvent lead to low PCE.