Quantum Dots Sensitized Solar Cell

*Vikram P. Bhalekar*

#### **Abstract**

In the modern and automated twenty-first century, with technological advancements, the scientific society has gifted a new alternative clean energy source (dye/quantum dot sensitized solar cells) to mankind as one of the applications of nanomaterials. Nowadays, the world is using a tremendous amount of fossil fuel for energy creation, the solar energy by using nanomaterials in the form of solar cells is a perfect alternative. In the present chapter, the emphasis has been given on the different techniques used by the researcher for synthesis of nanoparticles. The synthesis of quantum dots by simple cost-effective technique is covered with respect to PbS quantum dots. The working of quantum dot sensitized solar cells is also explained with its basic components. The narrow-band-gap semiconducting materials, which are suitable for solar cell application, are also listed in this context.

**Keywords:** solar cells, quantum dots, PbS, nanomaterials, UV, HRTEM, SAED

#### **1. Introduction**

The large existing need of the global energy is accomplished by burning fossil fuels. However, the inherent problems associated with the use of fossil fuel are their limited availability and the environmental issues. This forces mankind to look for new, more sustainable long-term energy solutions to provide the future energy resource. As the major renewable energy source, i.e., solar energy has the potential to become an essential component of future global energy production. The solar cell converts sunlight directly into electricity. In recent year, the concept of utilizing nanomaterialbased architectures in light energy conversion devices has emerged as an alternative to single-crystalline-based photovoltaic devices.

Besides the silicon solar cells, quantum dots sensitized solar cell (44%) and dye sensitized solar cells (33%) are two promising alternatives due to their cost-effective concepts for solar to electric energy conversion. The configuration of QDSSC consists of Photoanode (TiO2, ZnO, ZrO2, SnO2, etc., nanoparticle thin films), quantum dots (PbS, PbSe, CdS, CdSe, etc.), electrolyte (polysulfide, cobalt complex, etc.), and counter electrode (MoO3, CuS, CuSe, Pt, carbon black, etc.). Upon the illumination of light, the QDs generate the exciton (electron-hole pairs). Consequently, electron is injected into the photoanode to generate photocurrent, the hole is transported to the counter through redox couple toward electrode (Cathode). The overall power conversion efficiency (PCE) of a QDSSC is governed by the light harvesting efficiency, quantum yield for charge injection, and charge collection efficiency.

The chapter focuses on different approaches of preparation of nanomaterials. Synthesis of Quantum Dots (PbS) by simple cost-effective route. The structure of Quantum Dot Sensitized Solar Cell is given with requirement of basic components. The use of narrow-band-gap semiconductor, the materials suitable for the solar cell are also discussed in this topic.
