Two-Dimensional Materials for Advanced Solar Cells

Inorganic crystalline silicon solar cells account for more than 90% of the market despite a recent surge in research efforts to develop new architectures and materials such as organics and perovskites. The reason why most commercial solar cells are using crystalline silicon as the absorber layer include long-term stability, the abundance of silicone, relatively low manufacturing costs, ability for doping by other elements, and native oxide passivation layer. However, the indirect band gap nature of crystalline silicon makes it a poor light emitter, limiting its solar conversion efficiency. For instance, compared to the extraordinary high light absorption coefficient of perovskites, silicon requires 1000 times more material to absorb the same amount of sunlight. In order to reduce the cost per watt and improve watt per gram utilization of future generations of solar cells, reducing the active absorber thickness is a key design requirement. This is where novel two-dimensional (2d) materials like graphene, MoS2 come into play because they could lead to thinner, lightweight and flexible solar cells. In this chapter, we aim to follow up on the most important and novel developments that have been recently reported on solar cells. Section-2 is devoted to the properties, synthesis techniques of different 2d materials like graphene, TMDs, and perovskites. In the next section-3, various types of photovoltaic cells, 2d Schottky, 2d homojunction, and 2d heterojunction have been described. Systematic development to enhance the PCE with recent techniques has been discussed in section-4. Also, 2d Ruddlesden-Popper perovskite explained briefly. New developments in the field of the solar cell via upconversion and downconversion processes are illustrated and described in section-5. The next section is dedicated to the recent developments and challenges in the fabrication of 2d photovoltaic cells, additionally with various applications. Finally, we will also address future directions yet to be explored for enhancing the performance of solar cells.