Giant modulation of photoluminescence in CsPbBr3 films through polarization switching of PMN-PT

Abstract

CsPbBr3 shows excellent photoelectric properties such as a direct bandgap of 2.25 eV, large optical absorption coefficient, and strong luminescence intensity. Therefore, it is promising to be applied in LED devices. It is important to modulate and enhance photoluminescence (PL) intensity through external stimulus. Here, (001) CsPbBr3 films with nanocrystals were grown on the PMN-PT ferroelectric single crystal substrate, and its PL can be largely modulated by the ferroelectric polarization switching of PMN-PT. The saturated polarization of a 90 nm thick CsPbBr3 film induces a 67% increase in the PL intensity, which is due to piezoelectric strain passivated defects, resulting in decreased nonradiative recombination. However, the upward saturated polarization of the 40 nm thick CsPbBr3 film introduces a 55% decrease in the PL intensity, which can be attributed to the inner electric field separating the light-excited electron–hole pairs, thereby decreasing their radiative combination. This reversible and tunable photoluminescence is important for the development of advanced multifunctional optoelectrical devices.