Lead-free Cs3Cu2I5 perovskite vertical cavity surface emitting lasers with low threshold

Due to their non-toxicity, excellent thermal stability and optical properties, ternary copper halide perovskites, such as Cs3Cu2I5 and CsCu2I3, have been widely used in light-emitting devices (LEDs), UV and X-ray scintillation detectors. However, laser devices based on these materials have not been fully investigated. In this work, we demonstrated thermally stable Cs3Cu2I5 thin films, deposited by dual-source co-evaporation, possessing a photo-luminescence quantum yield (PLQY) up to 50.62%. Using the Cs3Cu2I5 as gain media, optically pumped perovskite vertical-cavity surface-emitting lasers (Pe-VCSELs) have been fabricated, integrating with a pair of distributed reflectors (DBRs), and shown lasing at 440 nm with a threshold of ∼1.12 μJ/cm2 pumped by a 288 nm fs laser. Furthermore, a monolithic dual-wavelength laser, with lasing wavelengths of 458.8 nm and 505.6 nm, has been achieved by depositing an additional gain layer and DBR mirror. Those results indicate that the lead-free ternary copper halide perovskites could be suitable as laser gain materials.