Seok Bin Kwon

A highly efficient and stable green-emitting mesoporous silica (MP)–(Cs0.4Rb0.6)PbBr3 perovskite composite for application in optoelectronic devices

We have, for the first time, reported a highly efficient MP–(Cs0.4Rb0.6)PbBr3 luminescent material for application in optoelectronic devices. MP–(Cs0.4Rb0.6)PbBr3 with red-emitting Sr2Si5N8:Eu2+ phosphor is applied to an InGaN blue chip and compared with green-emitting (Cs0.4Rb0.6)PbBr3 perovskite nanocrystals (NCs). MP–(Cs0.4Rb0.6)PbBr3 achieves a conversion efficiency of 80.9 lm W−1 under a forward-bias current of 150 mA. We propose MP–(Cs0.4Rb0.6)PbBr3 as a promising green-emitting material that can replace the conventional inorganic phosphor.

Millerite Core-Nitrogen-Doped Carbon Hollow Shell Structure for Electrochemical Energy Storage

Nickel sulfides have drawn much attention with the benefits of a high redox activity, high electrical conductivity, low cost, and fabrication ease; however, these metal sulfides are susceptible to mechanical degradation regarding their cycling performance. Conversely, hollow carbon shells exhibit a substantial electrochemical steadiness in energy storage applications. Here, the design and development of a novel millerite core-nitrogen-doped carbon hollow shell (NiS-NC HS) structure for electrochemical energy storage is presented. The nitrogen-doped carbon hollow shell (NC HS) protects against the degradation and the millerite-core aggregation, giving rise to an excellent rate capability and stability during the electrochemical charging-discharging processes, in addition to improving the NiS-NC HS conductivity. The NiS-NC HS/18h supercapacitor electrode displays an outstanding specific capacitance of 1170.72 F g-1 (at 0.5 A g-1 ) and maintains 90.71% (at 6 A g-1 ) of its initial capacitance after 4000 charge-discharge cycles, owing to the unique core-shell structure. An asymmetric-supercapacitor device using NiS-NC HS and activated-carbon electrodes exhibits a high power and energy density with a remarkable cycling stability, maintaining 89.2% of its initial capacitance after 5000 cycles.

Innovatively Continuous Mass Production Couette-taylor Flow: Pure Inorganic Green-Emitting Cs 4 PbBr 6 Perovskite Microcrystal for display technology

We report for the first time the mass production of Cs4PbBr6 perovskite microcrystal with a Couette-Taylor flow reactor in order to enhance the efficiency of the synthesis reaction. We obtained a pure Cs4PbBr6 perovskite solid within 3 hrs that then realized a high photoluminescence quantum yield (PLQY) of 46%. Furthermore, the Cs4PbBr6 perovskite microcrystal is applied with red emitting K2SiF6 phosphor on a blue-emitting InGaN chip, achieving a high-performance luminescence characteristics of 9.79 lm/W, external quantum efficiency (EQE) of 2.9%, and correlated color temperature (CCT) of 2976 K; therefore, this perovskite is expected to be a promising candidate material for applications in optoelectronic devices.