Synthesis Of Dyes And Their Performance In Dye-sensitized Solar Cells

The Problems of energy lacking and environment pollution have been increasing in thesedays, many countries are investigating new types of energy, which is more inexhaustible andwill not pollute circumstance, such as solar energy. So solar cells are invented.Since the yearof 1991, the development of Dye-sensitized solar cells (DSSC) based has been paid growingattention by more and more scientists, and dye-sensitizers play an important role in the DSSC.Most organic dye-sensitizers contain the structure of D-π-A, according to this, in this paperthree new triphenylmaine dyes, named MX11-13, were designed and synthesized. These dyesall contain triphenylamine as electron donor group, incorporate 2,2,6,6-tetramethyl-benzo[1,2-d;4,5-d’]bis[1,3]dioxole (TMBD), phenyl and 1,4-dipropoxybenzene(DPB) asπ-conjugated spacer, respectively, and hydrocyanic acid as electron accept group. The part ofπ-conjugated spacer, which can cause differences of the performance of dyes, is the highlightof the whole stuy.The three new dyes were prepared from triphenylamine and hydroquinone via oxidation,deoxidize reaction, bromonation reaction with NBS, Vilsmeier-Haack reaction, wittig reactionand Knoevenagel condensation reaction. The final compounds and intermediates not reportedin literatures were characterized by the melting point, IR, NMR, and MS spectra, respectively.And then the optical properties, electrochemical properties, and photovoltaic properties of theDSSC based on the MX11-13 were investigated.The dyes of MX11-13 all have two strang absorption between the 400 nm~600 nm, Themaximum absorption peaks (λmax) of MX11-13 were observed in visible region at 453, 453and 472 nm, respectively, and their HOMO–LUMO levels match with the level of TiO2,which suggested that these three dye-sensitizers are suitable for DSSC. From the research ofthe photovoltaic performance of DSSC based on MX11-13, we found out the performance ofMX13 is better than the others, with overall power conversion efficiency (η) 7.02%,short-circuit photocurrent density (Jsc) of 15.50 mA cm-2, open-circuit voltage (Voc) of 697 mV,and fill factor (ff) of 0.65. The fitted RCTincreases in the order of MX11 (54 ) < MX13 (82 ) < MX12 (151 ), which showed that the limitedηcollin device based on MX11 is one ofthe reasons for the lower IPCE, another main reason was the unfavorable dye aggregation onthe TiO2film.In this paper, we also designed two types of ruthenium dyes, some work of synthesis hasalready been done.