Series of New D-A-π-A Organic Broadly Absorbing Sensitizers Containing Isoindigo Unit for Highly Efficient Dye-Sensitized Solar Cells

Abstract

In this work, six new D-A-π-A sensitizers (ID1-ID6), with triarylamine as the electron donor; isoindigo as a auxiliary electron withdrawing unit; thiophene, furan, and benzene as the linker; and cyanoacrylic acid as the anchoring group, were synthesized through simple synthetic procedures and with low cost. Their absorption spectra were broad with long wavelength absorption maximum approximately at 589 nm and the absorption onset at 720 nm on the TiO(2) film. Electrochemical experiments indicate that the HOMO and LUMO energy levels can be conveniently tuned by alternating the donor moiety and the linker. All of these dyes performed as sensitizers for the DSSCs test under AM 1.5 similar experimental conditions, and a maximum overall conversion efficiency of 5.98% (J(sc) = 14.77 mA cm(-2), V(oc) = 644 mV, ff = 0.63) is obtained for ID6-based DSSCs when TiO(2) films were first immersed for 6 h in 20 mM CDCA ethanol solution followed by 12 h of dipping in the dye CH(2)Cl(2) solution. Electrochemical impedance measurement data implies that the electron lifetime can be increased by coadsorption of CDCA, which leads to a lower rate of charge recombination and thus improved V(oc).

New pyrido[3,4-b]pyrazine-based sensitizers for efficient and stable dye-sensitized solar cells

“…Such a phenomenon has been also observed in other dyes. 10 It should be noted that the PCE of the APP-III based cell was not the highest due to its relatively narrow absorption range and the lower J sc . In general, the J sc is related to the molar extinction coefficients and the absorption spectra of the dyes.…”

“…Furthermore, it is well established that for efficient solar energy conversion it is necessary to utilize dyes that possess high charge carrier mobility, broad absorption spectra and long-term stability. Recently, a series of novel D-A-p-A organic dyes 7 incorporating additional acceptors such as diketopyrrolopyrrole, 8 bithiazole, 9 isoindigo, 10 benzothiadiazole, 11 benzotriazole, 12 and quinoxaline 13 into the traditional D-p-A structure were reported and are receiving increasing attention. Inserting an auxiliary acceptor, which acts as an electron trap and increases the efficiency of charge separation facilitates electron transfer from the donor to the anchor.…”

Novel organic dyes based on thioindigo for dye-sensitized solar cells

“…Although, halogenations of indigo shifts the blue color of indigo to a reddish blue as in Tyrian Purple but a true red color is only possible when both imide (NH) residues of indigo are replaced by sulphur. Thioindigo is not found in nature and was synthesized over a hundred and ten years ago [10,11] Thioindigo has lost its importance as a vat dye, but a series of its halogenated and/or methylated forms are considered to be very important pigments of high durability. Can thioindigo (a more than a hundred and ten year old colorant) be revived as a dye sensitizer to be utilized in the modern high technology dye sensitized solar cells?…”

Advances in the synthesis and application of isoindigo derivatives

“…The last were finally converted to the target dyes (62) with α-cyanoacrylate fragment as anchoring group. 111 The best PCE of 5.98% was obtained for solar cells based on these isoindigo derivatives as acceptor material in active layers (Scheme 30).…”