*1.5.4 Air mass*

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 coefficient:

$$X = \frac{1}{\cos \theta} \tag{4}$$

**69**

**Figure 3.**

*(a–d) Nanostructures of different dimensions.*

*Nanostructures in Dye-Sensitized and Perovskite Solar Cells*

an electrical energy. The electrolytes containing I<sup>−</sup>/I3

**3. Nanostructures of inorganic materials**

**3.1 Zero-dimensional nanostructures**

**3.2 One-dimensional nanostructures**

several research groups [18].

reveal superior practical potential over micron-sized one.

number 10<sup>−</sup><sup>9</sup>

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

electron mediator between the TiO2 photoanode and the platinum-coated counter electrode. Therefore, the oxidized dye molecules (photosensitizer) are regenerated

dide ions) [16]. Regarding the working mechanism of perovskite solar cell, various

A major feature that discriminates various types of nanostructures is their dimensionality (**Figure 3a–d**). The word "nano" stems from the Greek word "nanos," which means dwarf. This word "nano" has been assigned to indicate the

has inverse relation with the surface area and reactivity thereby, nanoparticles

The significant progress has been made in the field of zero-dimensional nanostructures. A rich variety of physical and chemical methods have been proposed to synthesize zero-dimensional nanostructures. Recently, zero-dimensional nanostructures such as uniform particle arrays (quantum dots), heterogeneous particle arrays, core-shell quantum dots, onions, and hollow spheres are being obtained by

In the last decade, one-dimensional nanostructures have stimulated an increasing attention due to their importance in research and a wide range of potential

, i.e., 1 billionth of any unit [17]. It is believed that the size of particle

by receiving electrons from the I<sup>−</sup> ion redox mediator that get oxidized to I3

research groups reported differently; thereby, it is yet to be unprecedented.

<sup>−</sup> redox ions are used as an

<sup>−</sup> (triio-

*DOI: http://dx.doi.org/10.5772/intechopen.83803*

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