Enhanced Amplified Spontaneous Emission from All-Inorganic Perovskite Thin Films by Composition Engineering

摘要

All-inorganic CsPbBr_3 perovskite thin films are regarded as promising gainmedia to realize electrically pumped green laser diodes due to their goodstability. However, the amplified spontaneous emission (ASE) of CsPbBr_3perovskite thin films suffers from a relatively high threshold due to their highdefect density and large scattering loss. This work demonstrates high-qualityCsPbBr_3/CsPb_2Br_5 and CsPbBr_3/Cs_4PbBr_6 thin films using a vapor depositionmethod. Through rational design and modification on the compositionsof thin films, it is found that the existence of CsPb_2Br_5 or Cs_4PbBr_6 phase inCsPbBr_3 can dramatically improve photoluminescence and lengthen carrierlifetime. The mixed phase films show good crystalline quality with lower trapdensity and enhanced spatial confinement. As a result, the ASE threshold ofCsPbBr_3 perovskite thin film is reduced from 12.0 ± 0.2 to 10.1 ± 0.3 μJ cm~(?2)(with CsPb_2Br_5) and 10.2 ± 0.2 μJ cm~(?2) (with Cs_4PbBr_6). Furthermore, theoptical gain is increased from 10.4 ± 0.5 to 21.6 ± 0.9 cm~(?1) (19.5 ± 0.8 cm~(?1))with the participation of CsPb_2Br_5 (Cs_4PbBr_6) phase. The findings provide aneffective approach to lower the threshold of CsPbBr_3 lasers and shed light onthe potential of stable electrically pumped perovskite lasers.