  Multiple exciton generation (MEG) is a widely studied phenomenon in
semiconductor nanocrystals and quantum dots wherein photo-excited carriers
relax by generating additional electron-hole pairs. Here, we present the first
experimental observation of MEG and the same leading to giant external quantum
efficiency (EQE) in VO$_2$, a prototype strongly correlated material. By
employing a photoexcitation (lamda ~ 488 nm) of ~ 4.2 times the bandgap, EQE in
VO$_2$ is enhanced up to ~ 170 % at room temperature. Temperature dependent
experiments exhibit the direct relation between MEG and strength of electron
correlation and suggest that such a phenomenon could be exploited in large
number of strongly correlated materials for high performance solar cell
research in near future.
