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Multi-functional Quantum Dots Synthesis

Why are we interested in the Quantum Dots?

Quantum dots are nanometer-sized metal and semiconductor crystals with unique size-dependent chemical, optical and electronic properties.

▶ Advantages of Quantum dots

- Size-tunable electronic structures

- High luminescence efficiency

- Low thermal conductivity

- Inexpensive solution-based device fabrication

  (spin coating, ink-jet printing, spray coating, drop-casting)


▶ Nanomaterials Synthesis & Surface Engineering
'Design of nanoparticles for electronic and optoelectronic device devices'
Multicomponent nanostructures and superlattices are the most interesting class of electronic materials because novel unexpected properties can originate from the cross-talk between quantum confined components with different functionalities. This is a new area of nanomaterial research, and is virtually unexplored. In particular, core-shell morphology maximizes the interaction between the components and provides convenient platform for studying exciton-plasmon interactions and electronic coupling between metal and semiconductor at the nanoscale.  We will further explore general synthesis methods and applications for smart functional nanomaterials combined with desired optical, electronic, and magnetic properties


Pb-Free Quantum Dots Synthesis and Solar Cells Application
(Perovskite, III-V Semiconductor QDs)

▶ Background and Motivation
With the aim to equalize solar energy and the energy production cost of fossil fuels, researchers had turned their efforts towards the development of new generations of solar cells. Among the inorganic compounds, lead (Pb) based composites are especially attractive for photovoltaic applications due to the high light-absorption properties, but it is very toxic for human body. In order to solve this issue, the copper based composites as a light-absorption materials have been attracted for 


▶ Pb-free QDs Synthesis and Characterization

The aim of this research is to study environmentally friendly Pb-free solar cell materials and devices for next generation solar cell development.
1. We are developing new materials suitable for improving the efficiency of the solar cell and improving the efficiency of the quantum dot solar cell by controlling the bandgap of the nanomaterial by changing the shape and composition of the Quantum Dots using cation and anion exchange methods.


▶ Perovskite Quantum Dots and Device Application

The purpose of this research is to develop all-inorganic perovskite nanomaterials and devices for the development of next-generation solar cells.


1. Synthesis of Perovskite and double perovskite QDs.

2. Improvement of solar cell efficiency and stability by controlling the bandgap of perovskite nanomaterial by changing the composition of perovskite nanoparticles using cation and anion exchange method.



▶ Perovskite Quantum Dots Solar Cell
Our group demonstrated the electroluminescent solar cells with CsPbBr3 perovskite quantum dots (PQDs), utilizing solvent miscibility-induced ligand exchange process. Carboxylate esters with different alkyl chain length are used; longer carboxylate esters show a high miscibility with hydrophobic substances, leading to more efficient ligand exchange with preserving CsPbBr3 perovskite quantum dots, but at the same time undesired less film thickness because of the stripping-out of as-cast CsPbBr3 PQDs. Based on these results, we devise a suitably optimized solvent mixture of carboxylate esters to enable efficient ligand exchange with suppressed stripping-out phenomena. Therefore, the resultant CsPbBr3 PQD solids show a power conversion efficiency of 4.23% and a VOC of ∼1.6 V with green electroluminescence under applied voltage.

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