Morphological and opto-electrical properties of a solution deposited platinum counter electrode for low cost dye sensitized solar cells.

Although platinum (Pt) is a rare and very expensive material, Pt counter electrodes are still very commonly used for reaching high efficiencies in dye-sensitized solar cells (DSCs). The use of alternative cheaper catalyst materials did not yet yield equivalent efficiencies. In this work, we tried to understand how to reduce the amount of deposited Pt-material and simultaneously deliver higher DSC performances. We systematically compared the properties of Pt-counter electrodes prepared by simple solution deposition methods such as spray-coating, dip-coating, brushing with reference to the Pt-electrodes prepared by sputtering onto fluorine doped-tin oxides (FTOs). The morphological and structural characterizations of the deposited Pt-layers were performed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The composition of Pt-material was quantified using SEM electron dispersive X-ray (EDX) mapping measurements which were further compared with optical transmission measurements. Also contact angle and sheet resistance measurements were performed. By taking Pt-layers composition, morphology and structural factors into account, 9.16% efficient N3 dye based DSCs were assembled. The DSCs were subjected to various opto-electrical characterization techniques like current-voltage (I-V), external quantum efficiency (EQE), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and transient photo voltage (TPV) measurements. The obtained experimental data suggest that the Pt counter electrodes prepared by solution deposition methods can also reach high DSC device performances with a consumption of very little amount of Pt material as compared with sputtered Pt-layers. This process also proves that higher DSC performances are not limited to the usage of sputtered Pt-layer as counter electrode.

Study of interface properties in CuPc based hybrid inorganic-organic solar cells.

Metal-substituted phthalocyanine thin films such as copper-phthalocyanine (CuPc) are often used as photo-active and hole transporting layers (HTLs) in fully organic photovoltaic devices. In this work, CuPc is vacuum sublimated on an electron acceptor layer of mesoporous titania (TiO(2)) for the formation of hybrid TiO(2):CuPc solar cell devices. The performance of these hybrid solar cell devices was demonstrated without and with dye sensitization at the TiO(2):CuPc interface. The charge separation and photocurrent contribution at the interfaces in these multilayer hybrid devices was studied by using a variety of optoelectrical and photophysical characterization techniques. It is important to understand the fundamental interface properties of these multilayer hybrid solar cell devices for optimized performance.