As an emerging class of materials, two-dimensional (2D) materials have garnered significant attention in the field of photovoltaics due to their exceptional and unique properties. These materials, characterized by their atomically thin layers, offer promising opportunities for enhancing the efficiency and performance of solar energy conversion. This paper will focus on the principles governing 2D photovoltaic materials, providing an in-depth exploration of their characteristics and their applications in various types of photovoltaic devices. By examining the common features of these materials, the paper aims to offer readers a comprehensive understanding of what 2D materials are and how they can be effectively utilized in solar technology. Furthermore, the paper will also delve into the methods used for preparing and characterizing different types of 2D materials, offering insights into the cutting-edge techniques employed in the field. Additionally, the discussion will extend to the future research directions and potential applications of 2D materials in photovoltaics, encouraging readers to consider the broad scope of their impact. Through this exploration, the paper seeks to provide both scientific insights and practical knowledge for researchers and industry professionals interested in the rapidly growing field of 2D photovoltaics.