This chapter starts with a brief background required to set the stage for the design and engineering of 2D heterostructures for photovoltaic applications. It presents an overview of the 2D materials used in solar cells, their heterostructures, and their fundamental optical and electronic properties. It provides a brief description of the emerging 2D materials-based solar cells. The interfacial, as well as bulk defects, modulate the performance of solar cells up to a great extent. Therefore, defect passivation and interface engineering have been studied in great detail. The band alignment is also of utmost importance in order to reduce recombination and enhance carrier collection at respective electrodes. We have presented an overview of band alignment and its role in limiting solar cell performance. 2D materials have gained tremendous attention because of band gap tenability that finds application in photovoltaic devices. The chapter also portrays the overview of the materials that are used in solar cells along with their fabrication methods and characterization techniques. The spectroscopic, electrical, and some specific characterization techniques have been briefly described. Performance enhancement strategies for 2D heterostructure solar cells such as light-trapping technique, charge carrier dynamics, and interface engineering have been summarized in this chapter. The emerging solar cell technologies using 2D heterostructures have also been discussed. Overall, the chapter builds a thorough and step-by-step narrative about the design and engineering of 2D heterostructures for photovoltaic applications. 2D heterostructures have increasingly become important for future-generation solar cells due to their tunable band gap and extraordinary light-trapping properties. The chapter provides a comprehensive discussion on 2D heterostructures that find application in solar cell technology.