**2. Working principal of the DSSCs**

The working principal of the DSSCs is demonstrated in **Figure 2**. The wide bandgap nanocrystalline TiO2 (photoanode) semiconductor film is needed to be deposited on the conducting substrate (FTO) either by direct deposition or by doctor-blade method to provide the necessary large surface area to adsorb sensitizers (dye molecules). Upon absorption of photons, dye molecules are excited from

**Figure 2.** *The operating principle of the DSSCs.*

*Nanostructures in Dye-Sensitized and Perovskite Solar Cells DOI: http://dx.doi.org/10.5772/intechopen.83803*

*Nanostructures*

or with the I3

*1.5.4 Air mass*

coefficient:

two possible recombination pathways: direct recombination with the oxidized dyes

In Astronomy, air mass is direct path length through the earth atmosphere, expressed as a ratio relative to path length vertically upward, i.e., at the zenith. The intensity of solar radiations decreases with distance. Therefore, different air mass standards are being formulated to account for obstruction caused by the Earth's atmosphere. The air mass standard is denoted by "AM-X" in which X represents air mass

where *θ* is called solar zenith angle. This is defined as the angle between normal

of a given point on the earth and light path coming to that point from the Sun. The air mass standards are categorized into three different kinds: briefly, the AM 0 spectrum, for the solar radiation outside the atmosphere; AM 1 for flux of solar energy normal to the Earth; and AM 1.5 represents the solar energy flux impinging

The working principal of the DSSCs is demonstrated in **Figure 2**. The wide bandgap nanocrystalline TiO2 (photoanode) semiconductor film is needed to be deposited on the conducting substrate (FTO) either by direct deposition or by doctor-blade method to provide the necessary large surface area to adsorb sensitizers (dye molecules). Upon absorption of photons, dye molecules are excited from

thoroughly been studied in the literature by many researches.

*X* = \_\_\_\_ <sup>1</sup>

at the Earth's surface with 48.2° zenith angle.

**2. Working principal of the DSSCs**

<sup>−</sup> in the electrolyte (**Figure 1**). The latter process is dominant and has

*cos* (4)

**68**

**Figure 2.**

*The operating principle of the DSSCs.*

the HOMO to the LUMO. Once an electron is injected into the conduction band of the TiO2 photoanode, the dye molecule (photosensitizer) is oxidized. The injected electron is then transferred to TiO2 nanostructured photoanode through hopping kinetics which is finally extracted at load, where the work done is delivered as an electrical energy. The electrolytes containing I<sup>−</sup>/I3 <sup>−</sup> redox ions are used as an electron mediator between the TiO2 photoanode and the platinum-coated counter electrode. Therefore, the oxidized dye molecules (photosensitizer) are regenerated by receiving electrons from the I<sup>−</sup> ion redox mediator that get oxidized to I3 <sup>−</sup> (triiodide ions) [16]. Regarding the working mechanism of perovskite solar cell, various research groups reported differently; thereby, it is yet to be unprecedented.
