Stability of graphene–silicon heterostructure solar cells

The stability of undoped graphene–silicon heterostructure solar cells was investigated. Single‐layer graphene was grown by chemical vapor deposition on copper foil. Prior to the transfer of graphene to the silicon wafer, the flat Si(111) surface was passivated with hydrogen or methyl groups (CH 3 ). The conversion efficiency, η , of the H terminated Si device was negligible small (0.1%), whereas that of the CH 3 passivated Si was 2 and 4.2% at 100 mW (AM 1.5) and 20 mW of light intensity, respectively. After 28 days in ambient atmosphere η decreased only slightly to 1.5 and 3.7%. This small change of η is due to the high stability of the CH 3 passivated graphene–Si(111) interface. The methylated Si surface shows a high degree of chemical stability especially during the graphene transfer process.