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A Thiophene‐Based Anchoring Ligand and Its Heteroleptic Ru(II)‐Complex for Efficient Thin‐Film Dye‐Sensitized Solar Cells
Author(s) -
Mishra Amaresh,
Pootrakulchote Nuttapol,
Wang Mingkui,
Moon SooJin,
Zakeeruddin Shaik M.,
Grätzel Michael,
Bäuerle Peter
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201001863
Subject(s) - materials science , thiophene , dye sensitized solar cell , energy conversion efficiency , thin film , mesoporous material , electrolyte , photovoltaic system , chemical engineering , photochemistry , dielectric spectroscopy , electrochemistry , optoelectronics , nanotechnology , organic chemistry , electrode , chemistry , catalysis , ecology , engineering , biology
A novel heteroleptic Ru II complex (BTC‐2) employing 5,5′‐(2,2′‐bipyridine‐4,4′‐diyl)‐ bis (thiophene‐2‐carboxylic acid) (BTC) as the anchoring group and 4,4′‐ dinonyl‐2,2′‐bipiridyl and two thiocyanates as ligands is prepared. The photovoltaic performance and device stability achieved with this sensitizer are compared to those of the Z‐907 dye, which lacks the thiophene moieties. For thin mesoporous TiO 2 films, the devices with BTC‐2 achieve higher power conversion efficiencies than those of Z‐907 but with a double‐layer thicker film the device performance is similar. Using a volatile electrolyte and a double layer 7 + 5 μm mesoporous TiO 2 film, BTC‐2 achieves a solar‐to‐electricity conversion efficiency of 9.1% under standard global AM 1.5 sunlight. Using this sensitizer in combination with a low volatile electrolyte, a photovoltaic efficiency of 8.3% is obtained under standard global AM 1.5 sunlight. These devices show excellent stability when subjected to light soaking at 60 °C for 1000 h. Electrochemical impedance spectroscopy and transient photovoltage decay measurements are performed to help understand the changes in the photovoltaic parameters during the aging process. In solid state dye‐sensitized solar cells (DSSCs) using an organic hole‐transporting material (spiro‐MeOTAD, 2,2′,7,7′‐tetrakis‐( N , N ‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene), the BTC‐2 sensitizer exhibits an overall power conversion efficiency of 3.6% under AM 1.5 solar (100 mW cm −2 ) irradiation.