Highly efficient benzodifuran based ruthenium sensitizers for thin-film dye-sensitized solar cells

Abstract

a b s t r a c tThe synthesis of 4,4 0 -dibenzodifuran-2,2 0 -bipyridine derivatives as ligands of organic ruthenium dyes for DSSC applications is described. Two new heteroleptic ruthenium complexes have been prepared and compared with commercially available N719 and Z907 dyes, using dip dyeing and flow dyeing methods in large area testing cells prepared for industrial purposes. The newly synthesized dyes revealed higher solar-to-electric energy conversion efficiency (h), measured at the AM1.5G conditions, up to 21% compared to N719 and up to 46% compared to Z907, and external quantum efficiency of 53%. These results can be explained by enhanced light-harvesting of the benzodifuran moiety of the dyes that is related to photocurrent.

Synthesis and Characterization of Heteroleptic Ru(II) Complexes Based on 4,4′‐Bis((E)‐styryl)‐2,2′‐bipyridine as Ancillary Ligand and Application for Dye‐Sensitized Solar Cells

“…They all show the high‐energy part in the UV‐region at around 300 nm, which are assigned to the intraligand π – π * transition . The low‐energy absorption in the visible region for H1 – H4 showed broad bands between 432 and 572 nm dominated by the π – π * plus metal‐to‐ligand charge transfer (MLCT) transitions . The red shifts of 20 and 18 nm were observed for the lowest energy MLCT bands of H2 and H4 (572 and 568 nm) compared to H1 and H3 respectively due to the π ‐conjugation extension in the anchoring ligand caused by bridging the vinyl group between the carboxylate and bpy (or phen), which may result in enhanced light‐harvesting capabilities for the dyes in this series.…”

“…Also, heteroleptic ruthenium sensitizers have been investigated to further improve the enduring stability by introducing a bulky ancillary ligand on the hydrophilic N719 . To increase the power conversion efficiency region and the long‐term stability of the DSSCs, heteroleptic ruthenium(II) complexes have been developed using various ancillary ligands …”

Mechanistic Insights into the Stepwise Assembly of Ruthenium(II) Tris-heteroleptic Compounds

“…By this route, all reaction steps are performed in the same reaction flask without separation and purification of the intermediates. Since its publication, a large number of groups have adopted this procedure to prepare, mainly, cis -[Ru­(NN)­(dcbH 2 )­(NCS) 2 ] compounds. ,− It is stated that the reaction of [Ru­( p -cymene)­Cl 2 ] 2 in N , N ′-dimethyl­formamide (DMF) with the NN ligand at 333–353 K for 2 h results in the mononuclear [Ru­(NN)­( p -cymene)­Cl]Cl species, as shown in Figure . In the second step, dcbH 2 is added, and the temperature is increased to 423–433 K, leading to formation of the cis -[Ru­(NN)­(dcbH 2 )­Cl 2 ] complexes.…”

Buchwald–Hartwig Amination of Aryl Halides with Heterocyclic Amines in the Synthesis of Highly Fluorescent Benzodifuran-Based Star-Shaped Organic Semiconductors

“…Benzodifurans ( BDFs ), due to their p-type organic semiconductor properties, excellent light absorption and emission capability, and high hole mobility, are a group of compounds with a great potential application as luminescent and electroluminescent materials. − In addition, they are much less studied compared to benzodithiophenes widely used in optoelectronics. The appropriate molecular design of the BDF -based semiconductors allows for their application in many fields, including molecular switches and electrical regulators, − high-affinity fluorescent probes, potential therapeutic agents, dye-sensitized solar cell sensitizers, − polymer materials in polymer solar cells, − organic solar cells, , organic thin-film transistor materials, , and different layers in organic light-emitting diodes (LEDs). − …”