I have to proof that the connective $\displaystyle {|}$ is functionally complete.

According to the definition :

A set of connectives C is complete if whatever valuation function is definable in terms of the conectives of C

I have that $\displaystyle v(\phi | \psi) = 0 $ iff $\displaystyle v(\phi) = v(\psi) = 1$

As a suggestion I have : Proof that $\displaystyle (NOT \phi)eq(\phi|\phi)$

Can someone guide me?

Thank's