ABSTRACT
In this paper, we report a simple, rapid, and stable method for the continuous synthesis of highly stable Cs4PbBr6 perovskite microcrystals (MCs) using a microfluidic system. To demonstrate the potential application of Cs4PbBr6 MCs, the sample was fabricated with K2SiF6:Mn4+ phosphor onto InGaN blue chips as white-light-emitting diodes (LEDs). Our white-LED device achieved a high National Television Standards Committee value of 119% for backlight display, which indicated that the Cs4PbBr6 MC is a promising material for future applications.
ABSTRACT
Perovskite quantum dots (PQDs) attract significant interest in recent years because of their unique optical properties, such as tunable wavelength, narrow emission, and high photoluminescence quantum efficiency (PLQY). Recent studies report new types of formamidinium (FA) PbBr3 PQDs, PQDs with organic-inorganic mixed cations, divalent cation doped colloidal CsPb1-x Mx Br3 PQDs (M = Sn2+ , Cd2+ , Zn2+ , Mn2+ ) featuring partial cation exchange, and heterovalent cation doped into PQDs (Bi3+ ). These PQD analogs open new possibilities for optoelectronic devices. For commercial applications in lighting and backlight displays, stability of PQDs requires further improvement to prevent their degradation by temperature, oxygen, moisture, and light. Oxygen and moisture-facilitated ion migration may easily etch unstable PQDs. Easy ion migration may result in crystal growth, which lowers PLQY of PQDs. Surface coating and treatment are important procedures for overcoming such factors. In this study, new types of PQDs and a strategy of improving their stabilities are introduced. Finally, this paper discusses future applications of PQDs in light-emitting diodes.
ABSTRACT
All inorganic CsPbBr3 perovskite quantum dots (QDs) are potential emitters for electroluminescent displays. We have developed a facile hot-injection method to partially replace the toxic Pb2+ with highly stable Sn4+ . Meanwhile, the absolute photoluminescence quantum yield of CsPb1-x Snx Br3 increased from 45 % to 83 % with SnIV substitution. The transient absorption (TA) exciton dynamics in undoped CsPbBr3 and CsPb0.67 Sn0.33 Br3 QDs at various excitation fluences were determined by femtosecond transient absorption, time-resolved photoluminescence, and single-dot spectroscopy, providing clear evidence for the suppression of trion generation by Sn doping. These highly luminescent CsPb0.67 Sn0.33 Br3 QDs emit at 517â nm. A device based on these QDs exhibited a luminance of 12 500â cd m-2 , a current efficiency of 11.63â cd A-1 , an external quantum efficiency of 4.13 %, a power efficiency of 6.76â lm w-1 , and a low turn-on voltage of 3.6â V, which are the best values among reported tin-based perovskite quantum-dot LEDs.
ABSTRACT
Cadmium-free thick-shelled InP/ZnSeS/ZnS quantum dot (QD) was synthesized using the heating-up approach. This quantum dots was used in inverted quantum dots light emitting diode (QLED) devices. The brightness of the inverted QLED device can reach a brightness of over 10 000 cd m-2 , low turn-on voltage (2.2 V), and high power efficiency (4.32 lm W-1 ).
ABSTRACT
All-inorganic CsPbX3 (X=I, Br, Cl) perovskite quantum dots (PQDs) have been investigated because of their optical properties, such as tunable wavelength, narrow band, and high quantum efficiency. These features have been used in light emitting diode (LED) devices. LED on-chip fabrication uses mixed green and red quantum dots with silicone gel. However, the ion-exchange effect widens the narrow emission spectrum. Quantum dots cannot be mixed because of anion exchange. We address this issue with a mesoporous PQD nanocomposite that can prevent ion exchange and increase stability. We mixed green quantum-dot-containing mesoporous silica nanocomposites with red PQDs, which can prevent the anion-exchange effect and increase thermal and photo stability. We applied the new PQD-based LEDs for backlight displays. We also used PQDs in an on-chip LED device. Our white LED device for backlight display passed through a color filter with an NTSC value of 113 % and Rec. 2020 of 85 %.
