What is the black coating on the back of a throttle body?

I cleaned the throttle body of my car with carb cleaner not knowing the adverse effects it would have on the black coating on the back of the throttle body. I want to replace the black coating so my car will idle correctly. Does anyone know what that coating is made out of?

Thanks!
Hi, just wanted to add that the coating is actually not carbon build up. It is a paint-like substance on the throttle plate. I think it is used to help seal the plate to the housing of the throttle body.