Mateja Hočevar

Development of TiO2 pastes modified with Pechini sol–gel method for high efficiency dye-sensitized solar cell

A titanium oxide layer used for a dye-sensitized solar cell (DSSC) has to meet two opponent properties to assure a high efficiency DSSC: good connection between TiO2 grains and a large inner surface area. Three different paste formulations based on commercial nanocrystalline TiO2 powder (Degussa P25) are studied. Results confirm that modification of the TiO2 paste with the Pechini sol–gel method increases the surface area of the TiO2 layer while maintaining good connections between the nanocrystalline grains, consequently the efficiency of the DSSC increases from 1.8% to 5.3%. The structure and morphology of the TiO2 layers are described by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD).

Spatial characterization techniques for dye-sensitized solar cells

Spatial characterization techniques are applied to dye-sensitized solar cells (DSSCs). A comparison between transmittance imaging (TI), light-beam-induced-current (LBIC) scan and electroluminescence imaging is carried out. Detected types of inhomogeneities have different fingerprints by each applied technique. Electroluminescence (EL) is advantageous over TI because the electrical activity of the inhomogeneities influences the result. EL is also advantageous over the LBIC scan due to shorter acquisition time. Based on the above findings, EL has been used for characterization of DSSCs during outdoor short-term aging, showing that EL imaging is a proper method to follow the evolution of the inhomogeneities. Proof-of-concept EL inspection of a screen-printed dyesensitized solar module shows good uniformity.

Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) are recognized as one of the worlds leading innovation in nanosciences and photovoltaic technology. In contrast to the conventional silicon-based solar cells the demand on purity of materials for DSSC is lower and forecasted manufacturing costs are approximately halved which make the DSSCs attractive alternative. Nowadays the conversion efficiency of DSSCs exceeds 10% which makes it competitive with other thin film solar cells. In this chapter the structure and the fundamental operation of the DSSC are presented. Afterwards the properties and requirements for each individual component used in a DSSC are given. In addition advanced hybrid DSSC systems also are presented. In overall, the emphasis of this chapter is given to the involvement of sol-gel chemistry in the preparation of the individual DSSCs components, primarily of TiO2 layers and electrolytes.