A holistic and state-of-the-art review of nanotechnology in solar cells

New renewable energy technologies in different designs and forms are emerging every day as a result of the global awareness about the necessity of green transition and strict milestones set for 2050. Among all of the emerging technologies in this area, solar direct electricity generating systems (i.e. photovoltaic [PV], and photovoltaic-thermal [PVT] setups) are more popular not only due to the nature of solar energy, which is abundantly yet limitlessly available worldwide but also due to the recent advances in this field, making solar cells more efficient and cost-effective. The efforts in this framework are still ongoing, and from a research perspective, the use of nanotechnologies for the enhanced performance of such solar systems in various configurations and a wide variety of methods is something probably addressed more than any other approach. This article aims to present a thorough review of research activities in using nanostructures, nano-enhanced materials, nanofluids, and so on for solar direct electricity generating systems including the cells, the panel packages, and the supplementary equipment such as heat storage systems. The article provides the readers a deep understanding of the fundamentals of nanotechnology and how its knowledge has been developed over the years, how it has been integrated into the solar PV and PVT concepts, and what the state-of-the-art nature of this integrity looks like. Finally, our conclusions from the literature review process about the challenges, opportunities, risks, and benefits are presented and some proposals for future research in this area are given.