Heterogeneous Nucleation toward Polar‐Solvent‐Free, Fast, and One‐Pot Synthesis of Highly Uniform Perovskite Quantum Dots for Wider Color Gamut Display

Abstract

Inorganic halide perovskite quantum dots (IPQDs) hold great potentials for wide color gamut displays due to their high quantum yield, narrow, and composition‐tunable emissions. However, they are facing a big challenge to narrower size distribution and upscalable synthesis procedure. Here, different from the usual spontaneous nucleation, a one‐pot strategy, simply aided by uniformly heterogeneous nucleation agents, achieving mass production (≈1.8 g) with high product yield within short reaction time for various IPQDs is demonstrated. This method not only avoids the use of polar solvents, but also averts desirable transfer or injection operations. The heterogeneous nucleation takes place at surface chemical inert materials, which provide additional spatial separation effect, inhibiting the aggregative regrowth of primary IPQDs and thus enabling homogeneous nucleation and growth for various IPQDs. As a result, highly uniform IPQDs, as well as higher color purity, are achieved. Impressively, CsPbBr3 QD dispersion exhibits ultranarrow full width at half maximum of 15.5 nm. Overall, through the novel strategy, blue, green, and red light‐emitting diodes (LEDs) achieved with good optical properties contribute to a color gamut of 140% of the National Television System Committee standard, which is among the widest color gamut in the field of QLED and hence significant for the future high‐definition display.

Recent advances and prospects toward blue perovskite materials and light‐emitting diodes

“…Halide‐mixed perovskites are usually available in two pathways, that is, anion exchange and direct synthesis . For example, perovskite films obtained by one‐step spin coating exhibited a narrow emission spectrum over the entire visible range by changing the type of halides . Due to their single ionic charge, the rigidity of the cationic sub‐lattice and the effective vacancy‐assisted diffusion mechanism, the halide anions in perovskites are easily extracted and replaced by another halides …”

“…62,76 For example, perovskite films obtained by one-step spin coating exhibited a narrow emission spectrum over the entire visible range by changing the type of halides. 95,96 Due to their single ionic charge, the rigidity of the cationic sub-lattice and the effective vacancy-assisted diffusion mechanism, the halide anions in perovskites are easily extracted and replaced by another halides. 76 Anion exchange is considered as a relatively simple approach in obtaining mixed-halide perovskite QDs.…”

In Situ Passivation of PbBr64– Octahedra toward Blue Luminescent CsPbBr3 Nanoplatelets with Near 100% Absolute Quantum Yield

“…16 Although NCs with hybrid halogens (Cl and Br) can also exhibit narrow blue emissions, the unavoidable phase separation induced peak shift and its associated formation of traps are also limitations for achieving high QYs with long-term stability. 17 It is well accepted that quantum wells with large exciton binding energy (E b ) resulting from a strong quantum confinement effect is preferred for emission. 18 However, constructing pure CsPbBr 3 NPLs with low defect density for standard blue emission (∼460 nm) is still difficult.…”

Monochromatic LEDs based on perovskite quantum dots: Opportunities and challenges

“…In comparison, an advantage of the HI method is to synthesize nearly monodisperse nanocrystals. The HI technique generally provides a temporal separation of nucleation and growth and allows the controlled formation of nanocrystals with a narrow size distribution . The HI method was initially developed for the synthesis of nearly monodisperse cadmium chalcogenide NCs .…”

“…The HI technique generally provides a temporal separation of nucleation and growth and allows the controlled formation of nanocrystals with a narrow size distribution. 28 The HI method was initially developed for the synthesis of nearly monodisperse cadmium chalcogenide NCs. 29 However, the all-inorganic perovskite nanocrystals such as CsPbX 3 (X = Cl, Br, I) are mainly synthesized by using the HI method.…”