Bis‐Donor–Bis‐Acceptor Tribranched Organic Sensitizers for Dye‐Sensitized Solar Cells

Abstract

A new class of tribranched dye-sensitized solar cell (DSC) sensitizers carrying two conjugated donors and two acceptor/ anchoring groups is introduced. The approach leads to significantly different optical properties and enhanced stability

Dye‐Sensitized Solar Cells based on Organic Dual‐Channel Anchorable Dyes with Well‐Defined Core Bridge Structures

“…The absorption spectrum of dye DC4, containing a carbazole unit, showed a maximum absorption at l = 497 nm, red-shifted by 7 nm compared to dye DC2. The C=O stretching band at ñ = 1730 cm À1 , assigned to the carboxylic acid groups of free DC4 dye, disappeared in the IR spectrum of DC4 adsorbed onto TiO 2 film, indicating that both carboxylic acid groups are involved in the adsorption onto the TiO 2 surface; a result similar to observations made by Abbotto et al [17] The electrochemical properties were investigated by cyclic voltammetry (CV), to obtain the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the dyes (Table 1). Also, the absorption spectra of the DC dyes were red-shifted compared to the single-channel dye (D21L6), and the molar absorption coefficients of the DC dyes were much higher than that of D21L6 (e max = 27 700 m À1 cm À1 ; see Table 1).…”

“…The dianchoring mode of the DC dyes was confirmed by ATR-FTIR spectroscopy ( Figure S3). The C=O stretching band at ñ = 1730 cm À1 , assigned to the carboxylic acid groups of free DC4 dye, disappeared in the IR spectrum of DC4 adsorbed onto TiO 2 film, indicating that both carboxylic acid groups are involved in the adsorption onto the TiO 2 surface; a result similar to observations made by Abbotto et al [17] The electrochemical properties were investigated by cyclic voltammetry (CV), to obtain the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the dyes (Table 1). HOMO values (0.99, 1.03 V vs. NHE) were more positive than the I À /I 3 À redox couple (0.4 V vs. NHE).…”

“…[13] The close p-p stacking of dye molecules can lead to self-quenching of excited states and, hence, inefficient electron injection. [17][18][19] Herein we present an extension of the spiro design, aimed at further expanding the possibilities to improve the optical and energetic properties of sensitizers. [15] Another unique approach is the bridging of two chromophores into a spiro configuration, similar to ruthenium dyes.…”

“…Several dianchoring organic dyes have been synthesized for use in DSSCs, and they have demonstrated better solar-cell performances than analogous single D-p-A dyes, owing to an improved photoresponse, photocurrent, and stability. [17][18][19] Herein we present an extension of the spiro design, aimed at further expanding the possibilities to improve the optical and energetic properties of sensitizers. The new approach, based on an acceptor-p-bridge-donor-core bridge donordonor-p-bridge-acceptor (i.e., A-p-D-core bridge donor-Dp-A) structural motif, implies the use of two donors, two acceptors, and a core bridge donor.…”

Fabrication of dye sensitized solar cells with different anchoring mode based triphenylamine dyes

“…To avoid these problems, 1 The article is published in the original. several dianchoring organic dyes have been proposed to increase the optical density and binding strength of dyes onto titania by involving two anchoring groups in one molecule which may abate dye aggregation as well as charge recombination; and as a result an improved photoresponse, photocurrent, and stability [28][29][30] due to extension of π conjugation. Among these organic dyes, triphenylamine (TPA) based organic dyes shows promising performances in DSSC applica tion because of the non planar structure of TPA sup presses the dye aggregation as well as charge recombi nation and these dyes shows PCE up to 10% [31,32].…”