Dear punit,

In addition to their similar band gaps (1.1 eV for Si, 0.95 eV for FeS2) the electron affinities of Si and FeS2 are nearly identical (4.05

and 3.9±0.1 eV, respectively37,38), 

The work function= the electron affinity + (Ec-Ef), which depends on the doping.

For more information please refer to the link:http://environment.umn.edu/wp-content/uploads/2016/06/21-Leighton.pdf

Best wishes