Hyper-efficient LED technologies could enable applications from the visible-light LED bulbs in every home, to new displays, to gesture recognition using near-infrared wavelengths.
It’s snack time: you have a plain oatmeal cookie, and a pile of chocolate chips. Both are delicious on their own, but if you can find a way to combine them smoothly, you get the best of both worlds.
Researchers in The Edward S. Rogers Sr. Department of Electrical & Computer Engineering used this insight to invent something totally new: they’ve combined two promising solar cell materials together for the first time, creating a new platform for LED technology.
The team designed a way to embed strongly luminescent nanoparticles called colloidal quantum dots (the chocolate chips) into perovskite (the oatmeal cookie). Perovskites are a family of materials that can be easily manufactured from solution, and that allow electrons to move swiftly through them with minimal loss or capture by defects.
The work is published today in the international journal Nature.
“It’s a pretty novel idea to blend together these two optoelectronic materials, both of which are gaining a lot of traction,” says Xiwen Gong, one of the study’s lead authors and a PhD candidate working with Professor Ted Sargent. “We wanted to take advantage of the benefits of both by combining them seamlessly in a solid-state matrix.”
The result is a black crystal that relies on the perovskite matrix to ‘funnel’ electrons into the quantum dots, which are extremely efficient at converting electricity to light.
“When you try to jam two different crystals together, they often form separate phases without blending smoothly into each other,” says Dr. Riccardo Comin, a post-doctoral fellow in the Sargent Group. “We had to design a new strategy to convince these two components to forget about their differences and to rather intermix into forming a unique crystalline entity.”
The main challenge was making the orientation of the two crystal structures line up, called heteroexpitaxy. To achieve heteroepitaxy, Gong, Comin and their team engineered a way to connect the atomic ‘ends’ of the two crystalline structures so that they aligned smoothly, without defects forming at the seams. “We started by building a nano-scale scaffolding ‘shell’ around the quantum dots in solution, then grew the perovskite crystal around that shell so the two faces aligned,” explained coauthor Dr. Zhijun Ning, who contributed to the work while a post-doctoral fellow at UofT and is now a faculty member at ShanghaiTech.
The resulting heterogeneous material is the basis for a new family of highly energy-efficient near-infrared LEDs. Infrared LEDs can be harnessed for improved night-vision technology, to better biomedical imaging, to high-speed telecommunications.
The Latest on: Quantum dots and perovskite
via Google News
The Latest on: Quantum dots and perovskite
- Charge-separating heterostructures enable high-efficiency perovskite quantum dot photovoltaicson September 26, 2019 at 5:00 pm
Layer-by-layer deposition of the perovskite quantum dot (PQD) absorber layer. A colloidal solution of PQDs (Solution I) capped with long-chain surface ligands in an organic solvent is coated on a ...
- Photoluminescence Spectroscopy Optimizes Perovskite Quantum Dotson July 24, 2019 at 5:00 pm
Of particular interest for display applications are perovskite quantum dots (QDs), which combine the desirable properties of perovskite semiconductors with the excellent control of the light emission ...
- High efficiency perovskite quantum dot solar cells with charge separating heterostructureon June 28, 2019 at 2:22 am
Metal halide perovskite semiconductors possess outstanding characteristics ... Moreover, wider cation composition tunability and tunable surface ligand properties of colloidal quantum dot (QD) ...
- Quantum rebar: Quantum dots enhance stability of solar-harvesting perovskite crystalson May 22, 2019 at 12:43 pm
"Two of the technologies we pursue in our lab are perovskite crystals and quantum dots," says Sargent. "Both of these are amenable to solution processing. Imagine a 'solar ink' that could be printed ...
- What are quantum dots?on April 3, 2019 at 9:28 am
Although developed only recently, inorganic halide perovskite quantum dot systems have exhibited comparable and even better performances than traditional QDs in many fields. By preparing highly ...
- Nanocrystal “factory” makes mass manufacturing of quantum dots feasibleon March 19, 2019 at 2:03 am
NC State researchers have developed a microfluidic system for synthesizing perovskite quantum dots that drastically reduces manufacturing costs, can be tuned on demand to any color and allows for real ...
- Nanocrystal 'factory' could revolutionize quantum dot manufacturingon March 15, 2019 at 9:33 am
North Carolina State University researchers have developed a microfluidic system for synthesizing perovskite quantum dots across the entire spectrum of visible light. The system drastically reduces ...
- Perovskite Quantum Dots Deliver Coherent Single-Photon Emissionon February 25, 2019 at 8:38 am
and ETH Zurich showed that individual perovskite quantum dots could be used as a source for individual photons with precisely known and consistent properties, including wavelength. Each photon ...
via Bing News