Spectroscopy of d 6 Ru and Ir polypyridyl complexes for solar cells, OLED and NLO applications: Insights from theory Spectroscopy of d 6 Ru and Ir polypyridyl complexes for solar cells, OLED and NLO applications: Insights from theory Simona Fantacci Istituto CNR di Scienze e Tecnologie Molecolari (ISTM-CNR) & UdR INSTM Perugia Dipartimento di Chimica Via Elce di Sotto, 8, Perugia, ITALY

Computational approach Geometry Optimizations (CP-ultrasoft pseudopotentials) Calculation of excited states energies and oscillator strengths by Time Dependent-DFT (G03, ADF) Inclusion of solvation effects by a Polarizable Continuum Model (PCM) (G03, CP, ADF) Car-Parrinello (PBE//PWs) G03(B3LYP/DVZP), ADF(TZP,BP86) Methodology Overview Spectroscopic properties of Ru- and Ir- complexes: a) S. Fantacci, F. De Angelis, A. Selloni J. Am. Chem. Soc. 2003, 125, b) F. De Angelis, S. Fantacci, A. Selloni Chem. Phys. Lett. 2004, 389, 204. c) S. Fantacci, F. De Angelis,..., A. Selloni J. Am. Chem. Soc. 2004, 126, d) F. De Angelis, A. Tilocca, A. Selloni J. Am. Chem. Soc. 2004, 126, e) S. Fantacci, F. De Angelis, A. Sgamellotti,... J. Am. Chem. Soc , f) M. K. Nazeeruddin, F. De Angelis, S. Fantacci,... J. Am. Chem. Soc , g) F. De Angelis, S. Fantacci, A. Selloni, M. K. Nazeeruddin Chem. Phys. Lett. 2005, 415, 115. h) F. Tessore, D. Roberto,..., R. Ugo, F. De Angelis Inorg. Chem. 2005, 44, i) F. De Angelis, S. Fantacci, A. Sgamellotti,.., R. Ugo Dalton Trans. 2005, 2006, 852. l) C. Barolo, M.K. Nazeeruddin, S. Fantacci,… M. Grätzel Inorg. Chem. 2006, 45, m) M.K. Nazeeruddin,… F. De Angelis, S. Fantacci, M. Grätzel Inorg. Chem. 2006, 45, n) F. De Angelis, S. Fantacci,... M. Grätzel, M.K. Nazeeruddin Inorg. Chem. 2007, 46, in press. o) C. Dragonetti,… R. Ugo, F. De Angelis, S. Fantacci, A. Sgamellotti … Inorg. Chem. 2007, 46, in press.

Ru(II)-polypyridyl sensitizers for TiO 2 in dye sensitized solar cells (DSSCs) M. Graetzel, Nature, 2001, 414, 338.; M. Graetzel Inorg. Chem. 2005, 44, The dye, adsorbed on the semiconductor oxide surface, absorbs light in the visible region. 2.An electron is then transferred from the dye excited state to the TiO 2 conduction band. 3.The oxidized dye is regenerated by a support electrolyte. [Ru(4,4’COOH2,2’bpy)2(NCS)2], defined as N3 An efficient solar cell sensitizer should have broad range of visible light absorption, form long-living excited states with energies almost matching those of the TiO 2 conduction band and show a high thermal stability.

N3 4- Tuning the properties of Ru(II) TiO 2 sensitizers N3 N945 Effect of deprotonation and ligand substitution Bypyridine functionalization Ligand engineering Cl N621 N866

Energy (eV) Intensity (arb. units) Exp. Theor. MLCT (I) MLCT (II)  * ethanol water (III) Experimental and calculated absorption spectra of N3 in water solution LUMO HOMO-3 HOMO S. Fantacci, F. De Angelis, A. Selloni J. Am. Chem. Soc. 2003, 125, F. De Angelis, S. Fantacci, A. Selloni Chem. Phys. Lett. 2004, 389, 204. Md. K. Nazeeruddin, F. De Angelis,.., M. Grätzel J. Am. Chem. Soc. 2005, 127,

Modeling of TiO 2 surface Stoichiometric anatase Ti 38 O 76 cluster of nanometric dimensions exposing (101) surfaces B3LYP/3-21g* (NEQ-PCM) TD-DFT gap in solution: 3.20 eV KS gap in solution: 3.78 eV TD-DFT gap in vacuo: 2.82 eV KS gap in vacuo: 3.48 eV Experimental gap in acqueous solutions: 3.20 – 3.30 eV F. De Angelis, A. Tilocca, A. Selloni J. Am. Chem. Soc. 2004, 126,

Car-Parrinello molecular dynamics simulation of N3 adsorption on TiO 2 surface Starting from the final configuration we performed local geometry optimizations placing the protons on different sites.

1H + on dye / 1H + on TiO 2 0H + on dye / 2H + on TiO kcal/mol+11.0 kcal/mol +9.9 kcal/mol 1H + on dye / 3H + on TiO

Simulation of the Absorption spectrum Md. K. Nazeeruddin, R. Humphry-Baker, P. Liska, M. Grätzel, J. Phys. Chem. B, 2003, 107, Md. K. Nazeeruddin, F. De Angelis, S. Fantacci..,M. Grätzel J. Am. Chem. Soc., 2005, 127,

Ir(III)-polypyridyl complexes as phosphorescent dyes for OLED and NLO Strong and tunable emission in the visible region ( nm) Φ max =85% High transparency in the visible region and high NLO response (  β EFISH > esu) [Ir(ppy)2(5-X-1,10-phen)] + X=NMe 2 X=NO 2

Phosphorescent Ir(III) complexes for OLED phenylpyridine-phenanthroline (ppy-phen) phenylquinoline-phen X = Me, NMe 2, NO 2 (ppq-phen) M.K. Nazeeruddin, R.T. Wegh, C. Klein, Q. Wang, F. De Angelis, S. Fantacci, M. Grätzel, Inorg. Chem. 2006, 45, F. De Angelis, S. Fantacci, N. Evans, C. Klein,..., M. Grätzel, M.K. Nazeeruddin Inorg. Chem. 2007, 46, in press. C. Dragonetti, L. Falciola, P. Mussini, S. Righetto, D. Roberto, R. Ugo, F. De Angelis, S. Fantacci, A. Sgamellotti et al. Inorg. Chem. 2007, 46, in press.

Ir(III) cyclometallated complexes as multifunctional NLO Materials X=NMe 2 X=NO 2 L+2 L+1 L H H-1 L+2 L+1 L H H-1 Compound EFISH  b ( Dcm 5 esu -1 ) X=H-1270 X=Me-1565 X=NMe X=NO X=NO 2, NMe 2

Absorption spectrum, SOS-  X=NO 2 -NMe 2 Only negative contributions to  Positive and negative contributions to  C. Dragonetti, S. Righetto, D. Roberto, R. Ugo, A. Valore, F. De Angelis, S. Fantacci, A. Sgamellotti Chem. Comm. submitted phen-(ILCT) Ir->phen (MLCT)  =transition dipole moment  =excitation energy ground and excited state dipole moments

Conclusions Acknowledgments: Prof. Renato Ugo: Ir(III) complexes for OLED and NLO materials Prof. Michael Grätzel: TiO 2 Ru(II) photosensitizers and Ir(III) complexes for OLED Dr. Filippo De Angelis: TiO 2 calculations and CP simulations Theoretical and computational advances allow the study of systems of large and increasing complexity with unprecedented accuracy Quantitative agreement between theory and experimental optical properties of complex systems Interpretative and predictive power of modeling