Creating Fluorescent Perovskite Nanocrystals from Hardware Store Chemicals: A Synthesis Journey
0:00 Introduction to Perovskites: Perovskites are promising materials for solar cells due to their potential for high efficiency, but they face challenges with degradation, especially lead-based perovskites.
2:18 Perovskite Nanocrystals: Perovskite nanocrystals exhibit strong fluorescence, and their color can be tuned by changing the halide anion.
3:10 Mechanosynthesis: This synthesis uses ball milling to grind bulk perovskite into fluorescent nanocrystals, following a method described in a 2018 research paper.
3:45 Hardware Store Chemicals: The goal is to synthesize perovskite nanocrystals using readily available chemicals, including lead metal, nitric acid, sodium bromide, and cesium carbonate.
5:23 Hydrobromic Acid Synthesis: Hydrobromic acid is synthesized from sulfuric acid (drain cleaner) and sodium bromide. Older sulfuric acid samples are used for this step.
7:22 Hydrobromic Acid Distillation: Hydrobromic acid is distilled to minimize sulfuric acid contamination.
12:55 Sulfate Contamination Test: The distilled hydrobromic acid is tested for sulfate contamination using calcium chloride.
15:02 Cesium Bromide Synthesis: Cesium bromide is prepared by reacting cesium carbonate with the synthesized hydrobromic acid.
16:55 Lead Bromide Synthesis: Lead metal is melted and solidified (potentially to remove copper from copperized lead flashing), then dissolved in nitric acid. Lead bromide is precipitated by adding sodium bromide.
24:27 Lead Waste Disposal: Responsible lead waste disposal is emphasized, with the use of sulfide ions to precipitate insoluble lead sulfide.
26:08 DMSO as a Solvent: Dimethyl sulfoxide (DMSO) is introduced as a key solvent, with discussion of its properties, availability, and ethical concerns related to its use in alternative medicine.
31:33 Dissolving Lead and Cesium Bromides: Lead bromide and cesium bromide are dissolved in DMSO, with unexpected early fluorescence observed.
33:55 Growing Perovskite Crystals: Initial attempts to grow cesium lead bromide crystals by heating the DMSO solution are unsuccessful.
35:40 Copper in Lead Flashing: Concerns about copper contamination from the lead flashing are addressed with a test to assess copper content.
41:20 Ethanol Antisolvent Method: Ethanol is explored as an antisolvent to precipitate perovskite from the DMSO solution, showing promising initial results.