The chemical vapor deposition technique is the most popular for preparing high-quality graphene. Surface energy will dominate the nucleation process of graphene; thus, the surface energy problems involved in thin film growth are introduced first. The experimental tools to describe the growth process in detail are insufficient. So, a mass of simulation investigations, which can give out a very fine description of the surface atomic process, have been carried out on this topic. We mainly summarized the density functional theory works in unearthing the graphene nuclei process and mechanisms. In addition, some studies using molecular dynamics methods are also listed. Such a summary will be helpful to stimulate future experimental efforts on graphene synthesis.
Part of the book: Surface Energy
The power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have been reached the initial value when they emerged as dye sensitized solar cell (DSSC) in 2012. Immediately, the interests were drawn in this field worldwide. The researchers have improved the efficiency of PSCs up-to 22%, which was originally started from its initial value of 3.8%, just in 7 years. The rendering of long‐term stabilization and effective cost have special importance for PSCs since the instability issue remained idle in spite of those recently increased efficiency values attained by various research groups. In this way, the better improvements of PSC may increase extraordinary exhibitions as compared to alternate solar cells like organic solar cell (OSC) or DSSC devices. This chapter begins with a general discussion on the requirement for an economical clean energy conversion device. In section 2, fundamental properties of PSC are fit together with their device architecture and working mechanism. In section 3 proceeds with a review on fundamental photovoltaic parameters joined by current-voltage hysteresis. Furthermore, the stability and cost issues will be discussed in Sections 4 and 5. In the end of this chapter, we are discussing the challenges and opportunities based on the chapter content.
Part of the book: Emerging Solar Energy Materials