All-Inorganic Perovskite Nanocrystals with a Stellar Set of Stabilities and Their Use in White Light-Emitting Diodes

Abstract

We report a simple, robust, and inexpensive strategy to enable all-inorganic CsPbX3 perovskite nanocrystals (NCs) with a set of markedly improved stabilities, that is, water stability, compositional stability, phase stability, and phase segregation stability via impregnating them in solid organic salt matrices (i.e., metal stearate; MSt). In addition to acting as matrices, MSt also functions as the ligand bound to the surface of CsPbX3 NCs, thereby eliminating the potential damage of NCs commonly encountered during purification as in copious past work. Quite intriguingly, the resulting CsPbX3–MSt nanocomposites display an outstanding suite of stabilities. First, they retain high emission in the presence of water because of the insolubility of MSt in water, signifying their excellent water stability. Second, anion exchange between CsPbBr3–MSt and CsPbI3–MSt nanocomposites is greatly suppressed. This can be ascribed to the efficient coating of MSt, thus effectively isolating the contact between CsPbBr3 and CsPbI3 NCs, reflecting notable compositional stability. Third, remarkably, after being impregnated by MSt, the resulting CsPbI3–MSt nanocomposites sustain the cubic phase of CsPbI3 and high emission, manifesting the strikingly improved phase stability. Finally, phase segregation of CsPbBr1.5I1.5 NCs is arrested via the MSt encapsulation (i.e., no formation of the respective CsPbBr3 and CsPbI3), thus rendering pure and stable photoluminescence (i.e., demonstration of phase segregation stability). Notably, when assembled into typical white light-emitting diode architecture, CsPbBr1.5I1.5–MSt nanocomposites exhibit appealing performance, including a high color rendering index (R a) and a low color temperature (T c). As such, the judicious encapsulation of perovskite NCs into organic salts represents a facile and robust strategy for creating high-quality solid-state luminophores for use in optoelectronic devices.

Enabling Tailorable Optical Properties and Markedly Enhanced Stability of Perovskite Quantum Dots by Permanently Ligating with Polymer Hairs

“…Synthesis of Oleic Acid‐ and Oleylamine‐Cocapped CsPbBr 3 QDs via the Hot‐Injection Method : Oleic acid‐ and oleylamine‐cocapped CsPbBr 3 QDs were synthesized according to a method reported in the literature with minor modifications . In a typical experiment, Cs–oleate was first prepared by degassing 0.8 g Cs 2 CO 3 , 2.5 mL oleic acid, and 30 mL ODE in a reaction flask, followed by heating at 150 °C until the solution became transparent.…”

Potassium Doping to Enhance Green Photoemission of Light‐Emitting Diodes Based on CsPbBr3 Perovskite Nanocrystals

“…[ 1 ] Red, green, and blue light‐emitting diodes (LEDs) made from PeNCs have been demonstrated previously with highest recorded external quantum efficiencies (EQEs) over 20%. [ 2–9 ] Nevertheless, one of the key issues of PeNCs is their poor stability. PeNCs are prone to aggregate due to their high surface energy, which dramatically reduces their photoemission over time.…”

Bleifreie Halogenid‐Perowskit‐Nanokristalle: Kristallstrukturen, Synthese, Stabilitäten und optische Eigenschaften

“…So ist es wahrscheinlich, dass die Beschichtung von LFHP-NCs mit einer organischen oder anorganischen Schutzschicht die Stabilitäte rhçht. [125][126][127][128][129] Außerdem sollten weiterhin verschiedene Methoden der Defektpassivierung fürL FHP-NCs mit hçherer Qualitätu nd Stabilitäterschlossen werden. Es ist wichtig anzumerken, dass es noch kein ausreichendes mechanistisches Verständnis des Abbaus von LFHP-NCs gibt.…”