External-cavity-free low-threshold perovskite laser device and application thereof

An external-cavity-free low-threshold perovskite laser device, comprising:

• a gain medium, composed of a perovskite material or a mixed material containing the perovskite material;
• and
• at least one selected from the group consisting of a substrate, an electrode, and a charge transportation layer;
• wherein the laser device has no resonant cavity and is free of an additionally designed and machined resonant cavity;
• wherein the gain medium has a rough surface morphology comprising microcrystalline grains having a size ranging from several nanometers to hundreds of microns, and laser emission is generated by reflection and scattering of light among said microcrystalline grains without relying on end facets of the gain medium as a Fabry-perot cavity;
• wherein a laser emitting threshold of the laser device is lower than or equal to 100 μJ cm−2 under femtosecond laser pumping, and lower than or equal to 1 mJ cm−2 under picosecond or nanosecond laser pumping, or the gain medium is excited by continuous laser pumping to realize laser emission;
• and
• wherein an ingredient of the perovskite material is A′2An−1BnX3n+1, or ABX3, wherein n is a positive integer, A′ is an organic amine cation, A is a monovalent cation, B is a metal cation, and X is an anion.