**1. Introduction**

### **1.1 Background and motivation**

The predicted global energy needs, due to increasing concerns of environmental pollution in the twenty-first century, have motivated a great deal of efforts into the reduction of fossil fuel consumption followed exploration of clean, renewable, abundant, and eco-friendly renewable energy source technologies to enrich the quality of lives on this planet. Several renewable energy technologies are being investigated to evaluate their potential to address growing demand. These sources include wind turbines, hydropower, nuclear power plants, wave and tidal power, solar cells, solar thermal, and so on. Among these sources, photovoltaic technology, where sunlight is converted into an electrical energy, the so-called solar energy, has drawn considerable attention as it converts into a unique and potential solution. All renewable energy source technologies confirm a common dream, i.e., to capture one type of energy which later can convert into valuable and strategically important asset, that is, electric

energy. As the Sun provides a considerable amount of energy for our planet, the energy it provided is approximately 10,000 times more than global demand (i.e., 31,024 J/year); conversion of its 0.1% that is received by the Earth's surface using solar cells with power conversion efficiency of 10% would fulfill our present needs [1].
