Superlattices are Greener on the Other Side: How Light Transforms Self-Assembled Mixed Halide Perovskite Nanocrystals
Creators
- 1. Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States; International Doctoral Program in Science, Università Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia, Italy
- 2. International Doctoral Program in Science, Università Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia, Italy; Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- 3. Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
- 4. Notre Dame Integrated Imaging Facility, University of Notre Dame, Notre Dame, Indiana 46556, United States
- 5. Materials Characterization Facility, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- 6. Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States; Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, United States
- 7. Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
Description
Perovskite nanocrystal superlattices (NC SLs) are the nearest real-world approximations to monodisperse NC ensembles. NC SLs thus represent ideal model systems for evaluating the optical and structural stability of CsPb(I1–xBrx)3 NCs at a macroscopic level. Here, photoinduced changes to CsPb(I1–xBrx)3 NC SLs (0 < x < 1.0) are probed via in situ photoluminescence, X-ray diffraction, and electron microscopy. We find that prolonged (∼10–20 h) ultraviolet–visible irradiation causes irreversible PL blueshifts, photobrightening, and crystal structure contractions. These changes stem from gradual photoinduced I2 sublimation, which transforms CsPb(I1–xBrx)3 into CsPbBr3. Despite eliminating half of the initial halides from individual CsPb(I0.53Br0.47)3 particles, NCs within SLs remarkably preserve their initial crystallinity, cuboidal shapes, edge lengths, and size distributions. This work illustrates compositional control toward generating precisely engineered perovskite NC SLs. It also highlights iodide photo-oxidation as a hurdle that must be overcome if mixed halide perovskite nanomaterials are to be applied beyond fundamental studies.