Multicolor Biexciton Lasers Based on 2D Perovskite Single Crystalline Flakes

The biexciton is a quasi-particle created from two free excitons and can be applied for basic quantum operations, entangled light sources, and lasers. 2D lead-halide layered perovskites (LPs) naturally form organic-inorganic quantum wells (QWs), leading to high exciton binding energy and tunable band-gaps dependent on the QW thickness of . Although excitonic lasing has been reported for thicker LP-QWs, biexciton emissions and lasers from phase-pure LP-QWs as a function of remain largely unexplored. Here, a facile solution growth method for fabricating single-crystalline flakes (SCFs) of LP-QWs of (PEA)(2)(MA)(n)-1PbnI3n+1 (PEA = phenylethylammonium, = 1, 2, and 3) is reported. Further, multicolor amplified spontaneous emissions from biexciton states of (PEA)(2)(MA)(n)-1PbnI3n+1 ( = 1, 2, and 3) SCFs are demonstrated at 541 (green), 588 (yellow), 627 nm (red) with thresholds of 35.4, 15.1, and 5.8 mu J cm(-2) at 20 K, respectively. In order to offer cavities for these single-crystalline flakes, they are exfoliated into smaller flakes. Multimode lasing is shown at 586 and 627 nm for = 2 and 3 with threshold of 10.5 and 4.8 mu J cm(-2), respectively. The results of this study not only enrich the basic understanding of many-body excitonic interactions in 2D LPs but also provide insights for developing solution-processed multicolor lasers.