A molecularly engineered fluorene-substituted Ru-complex for efficient mesoscopic dye-sensitized solar cells
Chandrasekharam, Malapaka; Rajkumar, Ganugula; Srinivasa Rao, Chikkam; Suresh, Thogiti; Yella Reddy, Paidi; Yum, Jun-Ho; Khaja Nazeeruddin, Mahammad; Graetzel, Michael; Chandrasekharam, Malapaka; Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 607, India;; Rajkumar, Ganugula; Aisin Cosmos R&D Co. Ltd, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 607, India; Srinivasa Rao, Chikkam; Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 607, India; Suresh, Thogiti; Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 607, India; Yella Reddy, Paidi; Aisin Cosmos R&D Co. Ltd, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 607, India; Yum, Jun-Ho; Laboratory of Photonics and Interfaces, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland; Khaja Nazeeruddin, Mahammad; Laboratory of Photonics and Interfaces, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland; Graetzel, Michael; Laboratory of Photonics and Interfaces, Swiss Federal Institute of Technology (EPFL), Lausanne CH-1015, Switzerland
Журнал:
Advances in Natural Sciences: Nanoscience and Nanotechnology
Дата:
2011-09-01
Аннотация:
A new high molar extinction coefficient ruthenium(II) bipyridyl complex ‘cis-Ru(L1)(2,2′-bipyridine-4,4′-dicarboxylic acid) (NCS)<sub>2</sub>, BDF’, where L1=4,4-bis(9,9-dibutyl-9H-fluorene-2-yl)-[2,2] bipyridine, has been synthesized and characterized by Fourier transform infrared (FTIR), hydrogen nuclear magnetic resonance (<sup>1</sup>H-NMR) and electrospray ionization mass (ESI–MASS) spectroscopes. The dye, upon anchoring onto mesoporous nano-crystalline TiO<sub>2</sub> solar cells, exhibited a broader photocurrent action spectrum, with a solar-to-electric energy conversion efficiency (η) of 6.58% (J<sub>SC</sub>=14.66 mA cm<sup>−2</sup>, V<sub>OC</sub>=640 mV, fill factor=0.71) under sunlight at air mass (AM) 1.5, larger than the reference Z907 sensitized solar cell fabricated under similar conditions, which exhibited an η-value of 4.65% (J<sub>SC</sub>=11.52 mA cm<sup>−2</sup>, V<sub>OC</sub>=566 mV, fill factor=0.72). Absorption measurements and time-dependent density functional theory (TDDFT) calculations show that the increased conjugation length by introducing 9,9-dibutyl-9H-fluorene moiety relatively enhances the spectral response of the ancillary ligand and the corresponding BDF complex. The calculated dipole moments for BDF and Z907 are 17.71 and 16.34 Debye, respectively. The first three highest occupied molecular orbitals (HOMOs) of BDF have a t<sub>2g</sub> character, as observed in Z907, while HOMO-4 and HOMO-5 have considerable sizable mixing from Ru-NCS with π-orbitals of L1.
1.507Мб