Research Terms
Engineering Materials Sciences Thin Films Nanotechnology Optical Engineering
Keywords
Luminescent Nanomaterials Perovskite Quantum Dot Light Emitting Devices (Qleds) Quantum Dots
Industries
Advanced Materials & Products Photonics/Optics
UCF researchers have developed a simple, cost-effective method of fabricating perovskite-polymer composite materials with high photoluminescence quantum efficiency, exceptional moisture insensitivity and long-term stability. The new process resolves the instability issues that occur when organic-inorganic hybrid perovskite materials are exposed to external stresses (such as heat, water, light and electrical fields). Using the new method, manufacturers can now create and use highly stable perovskites to produce low cost, reliable, high-performance products. For example, the method can be used to create displays that withstand harsh environmental conditions—until now, no other means have been available.
Technical Details
The new method uses a swelling-deswelling microencapsulation process to create solution-processable organic-inorganic perovskites (OIPs). The swelling-deswelling encapsulation method involves three components: perovskite precursors, solvents, and polymer substrates. The substrates swell when brought into contact with the solvents and deswell when the solvents are removed.
The method starts with a perovskite precursor solution. The solution is processed directly onto a polymer matrix using a solvent combined with a procedure such as spin coating, dip coating or slot die coating. The solvent penetrates the polymer matrix and causes swelling, which allows the perovskite precursors to enter the polymer. Afterward, the solvent is removed from the polymer matrix, leaving the perovskite precursors in the matrix to react and form perovskite nanocrystals. The polymer subsequently deswells, forming a barrier layer around the perovskite nanocrystals to create a stable perovskite-polymer composite. Numerous types of perovskites, solvents and polymers may be used, as long as the polymers swell and deswell when solvents enter and exit them.
Researchers at the University of Central Florida have developed a low-cost, simple deep-dyeing method that can convert a polyethylene terephthalate (PET) polymer matrix into ultra-stable luminescent perovskite-polymer composites (PPCs) that demonstrate water resistance and heat stability. Due to their excellent color tunability, color purity, and water-/photo-stability, the PPCs are usable in displays, solid-state lighting, or other applications. The invention addresses a growing demand for improved, cost-saving manufacturing techniques that produce displays encompassing a large color gamut and high photoluminescence efficiency. With the invention, solid-state lighting (SSL) systems can meet specific lighting requirements while at the same time reducing or omitting unnecessary or even damaging portions of the spectrum. Applications include optical down-converters or emitters for display and lighting or active absorber or passive luminescent concentrators for solar photovoltaics.
Technical Details
The UCF invention comprises methods for fabricating stable, highly luminescent perovskite-polymer composites. It includes a swelling-deswelling encapsulation method involving three components:
For example, a perovskite-precursor solution is prepared: PbBr2 and CH3NH3Br are combined with a molar ratio of 1:3 in dimethylformamide to yield MAPbBr3. The solution is processed directly onto a polymer matrix through spin coating, dip coating, slot-die coating, inkjet printing, spray coating, or cotton swab painting. Next, a solvent (such as dimethylformamide) penetrates the polymers, causing them to swell and absorb the perovskite precursors. Finally, the solvent is driven out of the polymer matrix (by baking at 25-120 degrees Celsius for 2-10 hours), leaving the perovskite-precursors within the polymer matrix to react and form high quality, well-dispersed luminescent perovskite nanocrystals.
As the polymer substrate deswells (shrinks back), it forms a coherent barrier layer around the perovskite nanocrystals. This barrier protects them from water and oxygen from the surrounding environment. The perovskite-polymer composites possess high optical qualities showing narrow emission peaks and high photoluminescence quantum yield (PLQY). Numerous types of perovskites, solvents, and polymers may be used if the polymers swell and deswell when solvents enter and exit them.
High color quality white-light generation was demonstrated using green emissive MAPbBr3-polymer composites and red CdSe-based quantum dots as down-converters of blue LEDs. The LEDs provided color gamut coverage of a record 95 percent of Rec 2020, the color standard for ultra-high definition (UHD) TVs.
Partnering Opportunity
The research team is looking for partners to develop the technology further for commercialization.
Stage of Development
Prototype available.
A deep-dyeing strategy for ultra-stable, brightly luminescent perovskite-polymer composites, Journal of Materials Chemistry C, 2021,9, 3396-3402, https://doi.org/10.1039/D1TC00042J
