Biphenyl‐Amine‐Based D‐π‐A’‐π‐A Sensitizers for DSSCs: Comparative Photo‐Conversion Efficiency in Iodide/triiodide and Cobalt‐Based Redox Electrolyte and DFT Study

Abstract

We have designed and synthesized two dye molecules viz. MMR1 ((E)‐2‐cyano‐3‐(5‐((E)‐1‐cyano‐2‐(4′‐(dimethylamino)‐[1,1′‐biphenyl]‐4‐yl)vinyl)thiophen‐2‐yl)acrylic acid) and MMR2 (2‐((Z)‐5‐((5‐((E)‐1‐cyano‐2‐(4′‐(dimethylamino)‐[1,1′‐biphenyl]‐4‐yl)vinyl)thiophen‐2‐yl)methylene)‐4‐oxo‐2‐thioxothiazolidin‐3‐yl)acetic acid) with D‐π‐A’‐π‐A frameworks. The synthesized interfacial modifiers have dimethyl aniline as the donor group whereas cyanoacetic acid and rhodanine‐3‐acetic acid as the major acceptor groups in MMR1 and MMR2 respectively. The photophysical study in solution medium shows red shifted absorption maxima (λmax) for MMR2 vs MMR1. However, the molar extinction coefficient (ϵmax) for MMR2 is found to be lower than MMR1. The photovoltaic characterization of these molecules was carried out using iodide/triiodide and cobalt (II/III) based redox electrolytes for comparision. The molecules showed improved efficiency with the cobalt based electrolytes where MMR1 showed the highest power conversion efficiency (PCE) of 3.25% (Jsc=7.28 mA/cm2, Voc=0.713 V, FF=0.63). Further to have a deep insight into these synthesized molecules DFT studies were performed. The polarizability and hyperpolarizability values for the interfacial modifiers are calculated using DFT computation and are found to be correlated to the PCE.

Effect of metal ions in the electron-transfer mechanism on the photovoltaic performance of SALPHEN-based DSSC: experimental and theoretical studies

“…[1][2][3][4] Especially, aromatic azo derivatives containing a conjugated azo (-NQN-) group act as D-p-A charge-transfer chromophores, showing excellent photo-harvesting properties, which is attributed to the wide-ranging delocalized p-systems between the acceptor (A) and donor (D) units through the azo group. [5][6][7] Furthermore, their photophysical activity can often be enhanced by metal ion coordination, which influences their solar light-harvesting behavior. In particular, metal ions with incomplete valence shell configurations show intrinsic chemical characteristics when there are multi-dentate ligands in the metal complex, which has attracted considerable attention in the development of renewable energy technologies.…”

Exploration of 4-substituted thiophene-based azo dyes for dye-sensitized solar cells and non-linear optical materials: synthesis and an in silico approach

“…[9][10][11] The focus of current research has shifted from metal-containing dyes to metal-free organic dyes because of their push-pull nature, higher molar extinction coefficient (e), red-shifted absorption spectrum, intramolecular charge transfer (ICT), ease of electron transfer from an excited state dye to TiO 2 conduction band, and feasible charge transfer from donor (D) to acceptor (A). 9,[12][13][14] Organic sensitizers bonded through azobenzene, 15 stilbenes, 16 imines, 17,18 and biphenyls 19 with various Ds such as coumarin, 14,20 triphenylamine, 16 indoles, 21 and carbazoles 4 have demonstrated significant solar efficiency.…”

Cylindrical transparent conductive oxide-free dye-sensitized solar cells with treated flat titanium sheet

“… – 11 An electrolyte consisting of iodide/triiodide, Co(II)/Co(III), etc. redox couple is filled between the working and counter electrodes to sustain dye-regeneration and complete the DSSC working cycle 12 , 13 . Nowadays, research on DSSCs is not limited to developing efficient materials for the different components of DSSCs but also moving towards the proposal of novel device structures, which are efficient and cost-effective as compared to conventional solar cells.…”

“…redox couple is filled between the working and counter electrodes to sustain dye-regeneration and complete the DSSC working cycle. 12,13 Nowadays, research on DSSCs is not limited to developing efficient materials for the different components of DSSCs but also moving towards the proposal of novel device structures, which are efficient and cost-effective as compared to conventional solar cells. Removal of the costly TCO components of the conventional DSSCs to reduce the production cost of DSSCs has been attempted by several research groups including us in the past.…”