**Author details**

Narottam Das

where, "*a*" is the top length and "*b*" is the base length of the geometric shapes (such as, rectangle, trapezoid, and triangle). For a rectangular-shaped nano-grating profile, the AspR is "1" (i.e., the top and base length of the rectangle is equal) and for the triangular-shaped nano-grating profile, the AspR is "0" (i.e., the top length of the triangle is '0' compared to the base length of the triangle). However, for a trapezoidal-shaped nano-grating, the AspR is 0 < (*a*/*b*) < 1, that is, it lies between '0' and '1' (such as, 0.1–0.9). These nano-grating shapes play an important role for the light trapping inside the substrate that affects the conversion efficiency of solar cells. Therefore, an appropriate design of nano-structured grating is essential to reduce the light reflection losses and improve the conversion efficiency of solar cells.

The book "Nano-Structured Solar Cells" is divided into four parts.

length of the geometric shapes (such as, rectangle, trapezoid, and triangle).

4 Nanostructured Solar Cells

Part-1 discussed the general concepts of nano-structured solar cells. The requirement to produce solar or renewable energy with low production cost is indispensable dream of avoiding undue reliance on conventional energy systems. The emergence of third generation solar or photovoltaic system is in early stages that can fulfill the requirement of future demand. Solar cells can be considered by dyes, quantum dots, and perovskites for future generations dream.

**Figure 1.** Different types of nano-structured grating shapes or profiles. Where, 'a' is the top length and 'b' is the base

Part-2 discussed about different junction type nano-structured solar cells. To design a photovoltaic or solar cells, it is essential to understand the background of physics and operation of high-efficiency junction type solar cells. The surface recombination and passivation mechanisms, passivation schemes for cell surfaces are very important. The advanced cell structures and their fabrication schemes are able to achieve high conversion efficiency is demonstrated. These advanced cell design features have become highly active areas of investigation in the photovoltaic or solar energy industry for next generation's renewable or solar energy system.

Part-3 discussed about the organic and thin film nano-structured solar cells. This type of solar cell is one of the new energy sources, and a regenerated energy source is abundant and pollution-free which is environmentally friendly. The organic and thin film solar cell technology represents an alternative way to solve effectively the world's increasing energy shortage problem. The light trapping inside the solar cell is a critical issue for conversion efficiency Address all correspondence to: narottam.das@usq.edu.au

School of Mechanical and Electrical Engineering, Faculty of Health, Engineering and Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia

**Chapter 2 Provisional chapter**

#### **Third-Generation-Sensitized Solar Cells Third-Generation-Sensitized Solar Cells**

Muhammad Ammar Mingsukang, Mohd Hamdi Buraidah and Abdul Kariem Arof Muhammad Ammar Mingsukang, Mohd Hamdi Buraidah and Abdul Kariem Arof

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/65290

#### **Abstract**

The need to produce renewable energy with low production cost is indispensable in making the dream of avoiding undue reliance on non-renewable energy a reality. The emergence of a third-generation photovoltaic technology that is still in the infant stage gives hope for such a dream. Solar cells sensitized by dyes, quantum dots and perovskites are considered to be third-generation technological devices. This research focuses on the development of suitable and reliable sensitizers to widen electromagnetic (EM) wave absorption and to ensure stability of the photovoltaic system. This article discusses the basic principles and the progress in sensitized photovoltaics.

**Keywords:** third-generation solar cells, sensitized solar cells, dye-sensitized solar cells, quantum dot-sensitized solar cells, perovskite-sensitized solar cells
