The Design,Synthesis And Photovoltaic Performance Of Quinoid Dyes

This paper focus on the design and synthesise of quinoid molecules, and their application on dye-sensitized solar cells and organic photovoltaic solar cells. The research contents are as follows:1. Currently, photovoltaic performance of pn-type solar cells were limited by low performance of p-type dye-sensitised electrode, mainly due to its low photocurrent density. Maximizing short-circuit photocurrent density(Jsc) is a main mean to an end through developing highly efficient sensitizers. The compound QT-1 was prepared. The quinoidal thiophene based organic dye(QT-1) with a D-?-A structure was designed and synthesized for p n-DSCs. The dye was designed with the following structural characteristics:(i) They have a planar ?-system, favoring photoinduced intramolecular charge transfer and separation from the donor to the acceptor;(ii) That two cyano groups attached to quinoidal thiophene by a C-C double bond can stabilize the lowest unoccupied molecular orbital(LUMO) and lower the energy level, resulting in a relatively narrow optical band gap, which is particularly attractive for light harvesting at longer wavelengths;(iii) The quinoid sensitizer is simple in structure, and can be readily prepared using a short synthetic route. With I3-/I-, the best device showed a Jsc of 8.2 m A/cm2, Voc of 120 m V and a fill factor(FF) of 0.34, resulting in an overall efficiency(η) of 0.33%. Two peaks were observed with the values of 60% at 400 nm and 57% at 550 nm, which is among the highest reported efficiencies for p-DSCs. The Jsc is the highest value achieved in p-type DSCs, which is essential to construct high efficient pn-DSCs as mentioned above. With Co3+/Co2+, the best device showed a Jsc of 6.5 m A/cm2, Voc of 226 m V and a fill factor(FF) of 0.34, giving an overall efficiency(η) of 0.50%.2. Both polymer donor dyes and small molecules donor dyes ha ve the difficulties in synthesis and purification. We synthesize quinone small organic molecules donor dyes QT-2 and QT-3. Compared with the traditional small molecule materials, QT-2 and QT-3 connect the donor and acceptor by quinoid thiophene, featuring a large conjugated plane. They have the advantages of peculiar planar ?-conjugated structure and well known as electron acceptors and wide range of spectral absorption. Fundamentally solving the problems existing in the traditional polymers and small molecular materials, as for their structure is complicated and it is difficult to synthesize and separate them. The best device for QT-2 showed a Jsc of 7.15 m A/cm2, Voc of 730 m V and a fill factor(FF) of 0.35, resulting in an overall efficiency(η) of 0.33%. As for QT-3 showed a Jsc of 8.01 m A/cm2, Voc of 690 m V and a fill factor(FF) of 0.41, resulting in an overall efficiency(η) of 2.27%.