High work function large-area carbon black films as conductive, passivated, and hole-selective heterocontact layer for highly efficient solar cells

Carbon black (CB), which can be prepared by environmental pollutants such as waste tires, rice husks, feedstock oil, and coal tar, presents an overcapacity phenomenon. Further increasing the new applications of CB will help alleviate the pressure of environmental pollution. Here, we employed CB to selectively transport photogenerated carriers in silicon solar cells and broaden its application in solar cells. When used as the back field for p-type silicon solar cells, it achieves a power conversion efficiency (PCE) of 22.35 %. Similarly, when CB is incorporated as a component of the p-n junction in n-type silicon solar cells, it yields a PCE of 21.70 %. Such high numbers in the first study demonstrate the potential of the CB contacted silicon-based solar cells. A CB film with such high work function (6.3 eV) is obtained. And the CB/Si heterojunction can be fabricated using a simple, scalable doctor blade coating at room temperature and pressure. Large-scale new applications of conventional CB materials in the photovoltaic field help to realize the sustainability concept of green chemistry.