  We argue that the binding between doubly occupied (doublon) and empty (holon)
sites governs the incoherent excitations and plays a key role in the Mott
transition in strongly correlated Mott-Hubbard systems. We construct a new
saddle point solution with doublon-holon binding in the Kotliar-Ruckenstein
slave-boson functional integral formulation of the Hubbard model. On the
half-filled honeycomb lattice and square lattice, the ground state is found to
exhibit a continuous transition from the paramagnetic semimetal/metal to an
antiferromagnetic ordered Slater insulator with coherent quasiparticles at
$U_{c1}$, followed by a Mott transition into an electron-fractionalized AF$^*$
phase without coherent excitations at $U_{c2}$. Such a phase structure appears
generic of bipartite lattices without frustration. We show that doublon-holon
binding unites the three important ideas of strong correlation: the coherent
quasiparticles, the incoherent Hubbard bands, and the deconfined Mott
insulator.
