Research
Research Areas
Perovskite Semiconductor Electronics
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Perovskite Light-Emitting Diodes (PeLEDs)
Organic/inorganic hybrid perovskite has much higher color-purity and lower cost compared with organic emitters and inorganic QD emitters. Also efficiency of PeLED can be increased by fine stoichiometric tuning that prevents exciton dissociation, and nanograin engineering that reduces perovskite grain size, and concomitantly decreases exciton diffusion length.
Our study reduces the technical gap between PeLEDs and OLEDs or quantum dot LEDs and is a step toward the development of efficient next-generation emitters with high color purity and low fabrication cost based on perovskites.
[References]
1. Science (2015), 350, 1222
2. Advanced Materials (2015), 27, 7, 1248
3. Advanced Materials (2016), 28, 7515
4. Proc. Natl. Acad. Sci. U S A (2016), 113, 11694
5. Advanced Materials (2017), DOI:10.1002/adma.201700579
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Synthesis of Perovskite Nanocrystals
We synthesize and develop both metal halide perovskite nanocrystals (PeNCs) beyond the quantum size effect (diameter > exciton Bohr diameter) and perovskite quantum dots (QDs) under quantum size effect (diameter < exciton Bohr diameter) by using re-precipitation methods and hot-injection methods since 2014. Our research focuses on the optoelectronic properties of PeNCs for perovskite light-emitting diodes (PeLEDs) and solar cell. We reported various and comprehensive strategies to make monodisperse colloidal particles with fewer surface defects such as dopant alloying and ligand engineering. These high-quality PeNCs not only show high luminescence efficiency but also can be used to fabricate high-efficiency PeLEDs: current efficiency (~108 cd/A) and EQE (~23.4 %) in FA0.9GA0.1PbBr3 based PeLEDs. Furthermore, we report that highly efficient and uniform large-area PeLEDs can be realized through the use of colloidal PeNCsby a modified bar coating method, decoupling the crystallization of perovskites from film formation: external quantum efficiency (EQE) = 23.26% (for a pixel size of 4 mm2), 22.5% (for a large pixel area of 102 mm2) with high reproducibility. This provides a promising approach toward the development of large-scale industrial displays and solid-state lighting using perovskite emitters.
[References]
1. Nature Photonics (2021), 15,148–155
2. Nature Nanotechnology (2022),17, 590–597
3. ACS Nano (2017), 11, 7, 6586-6593
4. Nano Energy (2017), 38, 51-58
[Patent]
1. Perovskite nanocrystalline particles and optoelectronic device using same (2019)
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Perovskite Solar Cells
The organic-inorganic hybrid perovskite solar cell, which is cheap and easy-to-make photo-absorption materials, has highly increased the power conversion efficiency of thin film solar cells in the recent years. We also used the work function controllable conducting polymers as the efficient charge extraction interlayer in perovskite solar cells.
[References]
1. Energy & Environmental Science (2016), 9, 12
2. Energy & Environmental Science (2016), 9, 932
3. Advanced Materials (2014), 26, 37, 6461
4. Advanced Materials Interfaces (2016), 3, 1500678