Structural features of indoline donors in D–A-π-A type organic sensitizers for dye-sensitized solar cells

Abstract

We report three newly synthesized D-A-π-A metal-free organic sensitizers for dye-sensitized solar cells (DSSCs) based on benzo[c][1,2,5]thiadiazole as an internal acceptor (A) and N-substituted indolines fused with cyclopentane or cyclohexanes...

Indoline-Based Donor-π-Acceptor Visible-Light Responsive Organic Dyes for Dye-Sensitized Solar Cells: Co-sensitization with Squaraine Dye for Panchromatic IPCE Response

“…The indoline-based donor moiety is very important to achieve high DSSC device efficiency for the D-π-A and D-A-π-A dye architectures. ,− Further, most of the indoline-based donors are either in-plane functionalized on the N-atom of the indoline unit with alkyl and aryl (phenyl, benzyl, etc.) groups or fused cyclopentane and cyclohexane with the indole unit. − But here, we report a new strategy to functionalize the indoline donor with out-of-plane alkyl groups and in-plane alkyl or glycolic groups by the reduction of indolium salts with NaBH 4 at room temperature (Scheme ). AKT dyes were synthesized by a Knoevenagel condensation reaction between the cyanoacetic acid and corresponding aldehyde derivatives 8a – c .…”

“…Further, the indoline-donor-based D-π-A dye gives a hypsochromic shift in the intramolecular charge transfer (ICT) absorption band (which is almost negligible for D-A-π-A dyes) after anchoring on the TiO 2 surface compared to the solution, and the shift in the ICT absorption band makes this dye attractive for light-harvesting from high energetic visible regions . Furthermore, indoline-donor-based D-π-A and D-A-π-A dyes have achieved 4.0–10% DSSC device efficiencies ,− and showed better donor ability compared to a triphenylamine donor. , By keeping the above dye design and principles in mind, a series of metal-free indoline-based D-π-A visible-light active organic dyes with a mono- or bi-thiophene unit, where the indoline unit is wrapped with alkyl-alkyl and alkyl-glycolic (alkyl-TEG) chains, have been designed and synthesized (Figure ). The photophysical, electrochemical, theoretical, and DSSC device characterizations have been studied systematically to determine the effect of mono-thiophene, bi-thiophene, alkyl-alkyl, and alkyl-TEG on the photophysical, electrochemical, and DSSC device efficiencies.…”

Monitoring the dependence of the photovoltaic properties of dye-sensitized solar cells from the structure of D–A–π–A-type sensitizers with a 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazole donor building block

“…6 Since the discovery of the first representative of a dye of this series, WS-2 , by Zhu et al in 2011, 7 this structure was intensely modified in order to reveal the effect of individual moieties in sensitizers on the photovoltaic properties of DSSCs. 8–14 Finally, the power conversion efficiency reached 12.5%. 15 Since complicating the structure of sensitizers does not always guarantee a high PCE, the D–A–π–A sequence can be considered the optimal structure in terms of the ratio of synthetic costs and the resulting efficiency.…”

Molecular Environment Effects That Modulate the Photophysical Properties of Novel 1,3-Phosphinoamines Based on 2,1,3-Benzothiadiazole

“…Molecular environment effects appear as an intriguing phenomenon that give rise to unique photophysical properties of compounds both in the solid state and in solution, e.g., mechanochromism [1], solvatochromism [2], aggregation-induced emission [2], etc. These properties open up prospects for the design of smart materials for sensors, [3] optoelectronic devices [4], and biological labelling [5]. For these purposes, 2,1,3-benzothiadiazole (btd) derivatives have been extensively studied owing to the prospects for their applications in organic light-emitting diodes [6], luminescent sensors [7], and bioimaging [5].…”