  Molecular motors are essential to the living, they generate additional
fluctuations that boost transport and assist assembly. Self-propelled colloids,
that consume energy to move, hold similar potential for the man-made assembly
of microparticles. Yet, experiments showing their use as a powerhouse in
materials science lack. Our work explores the design of man-made materials
controlled by fluctuations, arising from the internal forces generated by
active colloids. Here we show a massive acceleration of the annealing of a
monolayer of passive beads by moderate addition of self-propelled
microparticles. We rationalize our observations with a model of collisions that
drive active fluctuations to overcome kinetic barriers and activate the
annealing. The experiment is quantitatively compared with Brownian dynamic
simulations that further unveil a dynamical transition in the mechanism of
annealing. Active dopants travel uniformly in the system or co-localize at the
grain boundaries as a result of the persistence of their motion. Our findings
uncover the potential of man-made materials controlled by internal activity and
lay the groundwork for the rise of materials science beyond equilibrium.
