Organic–Inorganic Hybrid Silicon Solar

The real challenge of solar cells can be summarized to reduce the cost while increasing the conversion efficiencies. Organic–inorganic hybrid silicon solar cell is a newly developed type of solar cells which is expected to realize above requirement. It can inherit the high efficiency and reliability of the silicon material and the flexibility, light weight, and affordability of the organic materials. In this new type of devices, an organic layer is generally spread on the silicon to form the heterojunction, where the silicon wafer is adopted as the optical absorber. To reduce cost, ultrathin silicon wafer should be the best choice if only it can absorb enough sunlight to support the high efficiency. Therefore, light-trapping nanostructures, like silicon pyramid, nanowire, nanocone, and silver nanoparticle, have been widely utilized to improve the light absorption. As a consequence, the preparation of ultrathin silicon wafer and various silicon nanostructures is an important fundamental for the organic–inorganic hybrid silicon solar cells. In addition to form heterojunction with silicon, the other function of the polymer layer is to transport holes. So, the hole-transporting ability is one of the main criteria for choosing the polymer. In these days, PEDOT:PSS is most widely used and thought to be the best choice. Because silicon is inorganic, it is a challenge to form a perfect interface contact with the PEDOT:PSS; thus, there always exists abundance of defect structures and defect states on the organic–inorganic interface. These interface defects are another limitation for the efficiency of the organic–inorganic hybrid silicon solar cells. So, fabrication technology is another very important aspect to ensure the high efficiency of such type of hybrid solar cells. It includes modifying the surface wettability of silicon to improve the junction quality and importing effective passivation for the organic–inorganic interface to reduce the recombination centers. Considering these factors, in this chapter, firstly, some recent works on the preparation of crystal silicon membrane and several silicon nanostructures have been summarized by us; then, the basic process, especially the passivation technologies, in fabricating the heterojunction is given. We hope this summary is helpful for the future development of organic–inorganic hybrid silicon solar cells.