# Self-Assembled Multinuclear Complexes for Cobalt(II/III) Mediated Sensitized Solar Cells
## 2 Experimental Section
### Methods  
Absorption spectra of solutions and of sensitized films were recorded in transmission mode with a Jasco V 570 at RT conditions against either a reference solvent or air respectively. \({}^{1}\)H and \({}^{13}\)C NMR spectra were obtained with a Varian 400 MHz referring to the solvent residual peak.  
Mass spectroscopy was carried out with a LCQ Duo Thermo Finnigan instrument equipped with an ESI (ElectroSpray Ionization) source. T = 160 \({}^{\circ}\)C, source voltage = 4.57 KV, capillary voltage = 10.32 V, flow rate = 25 \(\upmu\)L/min.  
Cyclic voltammetry analyses were obtained with a PGSTAT 302/N potentiostat in a three electrode-cell using glassy carbon or dyed films as working electrodes, a platinum wire as the counter electrode, and standard calomel electrode (SCE) as the reference.  
Infrared spectra were recorded with a Bruker Vertex 70 FTIR (Fourier Transform Infrared spectrometer) in diffuse reflectance mode using the powder of each of the synthesized compounds dispersed in KBr against a blank KBr at RT under nitrogen flow.  
J/V (Current density/voltage) curves of the DSSCs were obtained with a PGSTAT 302/N potentiostat setting under cyclic voltammetry mode. Illumination of the cells was achieved with an Abet sun simulator equipped with an AM1.5 G filter (the lamp irradiance was set to 100 mw/cm\({}^{2}\)). The photoaction spectra (IPCE (Incident Photon to Current Conversion Efficiency) vs. \(\lambda\)) were obtained under monochromatic illumination obtained by coupling a 300 W Luxtel xenon lamp with a Newport Cornerstone CS-260 monochromator. Illumination was orthogonal to the DSSCs via a Newport liquid light guide, illuminating a spot size of ca. 1.5 cm\({}^{2}\). A National Instruments PXI 4130 Source Measure Unit in a PXI-1033 chassis recorded the photocurrent from the cell under test, while a PXI-4065 Digital Multimeter simultaneously measured the voltage from a Thorlabs PDA100A-EC Si amplified detector monitoring part of the irradiating light reflected by a quartz beamsplitter.  
Emission spectra were measured with an Edinburgh FS920 spectrofluorimeter equipped with a 450 W arc Xe lamp and a photomultiplier tube as detector.  
Transient absorption and emission spectroscopy was carried out on both the fluid solution and on stained solid thin films in contact with 0.1 M LiClO\({}_{4}\)/ACN (dyed TiO\({}_{2}\) and ZrO\({}_{2}\) films) with a time resolved spectrometer described elsewhere [19] at an excitation energy of 10 mJ/cm\({}^{2}\)/pulse. Within the time interval of interest, the S/N ratio of the traces was optimized by pre-amplifying the oscilloscope input signal with a suitable impedance.  
Luminescence decay kinetics in the ns range were obtained by single-photon counting with TC-SPC apparatus (PicoQuant Pichapr 300) equipped with a nanosecond 460 nm LED source.  
Electrochemical impedance spectroscopy (EIS) was carried out on illuminated DSSCs under open circuit potential (Voc) by applying a sinusoidal perturbation in the 10\({}^{5}\)-10\({}^{-1}\) Hz range with an amplitude of 10 mV. The electron lifetimes were obtained from the -Z\" vs. frequency plot according to: \(\tau=\frac{1}{2\pi f_{MAX}}\) where \(f_{MAX}\) represents the frequency of the maximum of the imaginary part of the impedance associated with the TiO\({}_{2}\)/electrolyte interface.  
The open circuit photovoltage decay (OCVD) experiments were collected in chronopotentiometry (zero current) mode. After a steady photopotential was attained, the illumination was suddenly turned off using a shutter and the photovoltage decay was sampled at \(5\times 10^{-4}\) s intervals in an experiment with the total duration of 5 s. The lifetime \(\tau_{el}\) was calculated according to \(\tau_{el}=-\frac{KT}{c}\Big{(}\frac{\partial V_{\text{OC}}}{dt}\Big{)}^{-1}\).