The purpose of this special issue is to investigate the existence of different methods on the efficiency of solar cells. As it is known, many factors affect the efficiency of solar cells. One of them is the defects that occur in the semiconductor material. Defects in the semiconductor material will significantly affect the conduction of carriers. We are considering applications of radiation, which we think maybe one of the alternative methods to eliminate this particular number of defects. Developing industry, increasing population, the development of systems that consume more energy, the increase in energy consumption, and the rapid depletion of traditional energy sources have caused energy resource concerns for future generations. To eliminate these concerns, alternative energy sources to traditional energy sources have been trying to be developed. Among these energy sources, renewable energy sources are seen as the biggest energy source potential in the future. Among the renewable energy sources, solar cells are one step ahead due to the advantages they have. While most inorganic semiconductors are stable under high X-ray flux of focused X-ray beams, semiconductors with organic components are prone to various degradation mechanisms. Therefore, it is important to investigate the effects of X-rays on the nanoscale performance and elemental distribution of solar cells. Efficiency in a photovoltaic power system depends on many parameters. It is difficult to minimize or eliminate the effects of these parameters on the system without knowing their characteristics. If we can eliminate the defects that occur in the system, we can increase efficiency. It is known that X-rays have a constructive effect in medicine as well as a destructive effect on cells. Therefore, it is important to examine and compare these effects, especially at different doses and different energies. The advantages and disadvantages of X-rays, which may occur in the efficiency of photovoltaic solar cells, in eliminating defects at different energies and different doses can be compared.