Lasing actions in organo-lead halide perovskite films have been
heavily studied in the past few years. However, due to the disordered nature of
synthesized perovskite films, the lasing actions are usually understood as
random lasers that are formed by multiple scattering. Herein, we demonstrate
the miscellaneous lasing actions in organo-lead halide perovskite films. In
addition to the random lasers, we show that a single or a few perovskite
microparticles can generate laser emissions with their internal resonances
instead of multiple scattering among them. We experimentally observed and
numerically confirmed whispering gallery (WG)-like microlasers in polygon
shaped and other deformed microparticles. Meanwhile, owing to the nature of
total internal reflection and the novel shape of the nanoparticle, the size of the
perovskite WG laser can be significantly decreased to a few hundred
nanometers. Thus, wavelength-scale lead halide perovskite lasers were realized
for the first time. All of these laser behaviors are complementary to typical random lasers in perovskite film and will help the
understanding of lasing actions in complex lead halide perovskite systems.