Thermodynamic Control in the Synthesis of Quantum-Confined Blue-Emitting CsPbBr₃ Perovskite Nanostrips

Abstract

Size control is critical in the synthesis of quantumconfined semiconductor nanocrystals, otherwise known as quantum dots. The achievement of size-uniformity and narrow spectral line-width in quantum dots conventionally relies on a very precise kinetic control of the reactions, where reaction time plays a significant role in defining the final crystal sizes and distribution. Here, we show that synthesis of quantum-confined perovskite nanostrips could be achieved through a thermodynamically controlled reaction, using a low-temperature and ligand-rich approach. The nanostrip growth proceeds through an initial onedimensional (1D) nanorod stage, followed by the lateral widening of the rod to form a two-dimensional (2D) nanostrip. The spectral characteristics of the final product remain unchanged after prolonged reaction, indicating no signs of crystal ripening and confirming the thermodynamic nature of this reaction. The CsPbBr 3 perovskite nanostrips were highly uniform and emit at a deep-blue wavelength of 462 nm with a remarkably narrow line-width of 13 nm. This corresponds to color coordinates of (0.136, 0.049) on the CIE 1931 color space, which fulfils the stringent Rec. 2020 standard for next-generation color displays. The well-passivated nanostrips also possess negligible defects and provide a near-unity photoluminescence quantum yield at 94%. Crucially, the achievement of blue emission through a pure-halide perovskite circumvents the problems of spectral instability that are frequently experienced in mixed-halide perovskite systems. The convenience and scalability of our thermodynamic approach, coupled with the excellent optical attributes, would likely enable these quantum-confined perovskite systems to be the preferred method toward color control in trichromatic display applications.

Deep Blue Layered Lead Perovskite Light‐Emitting Diode

“…[5] 1) One method is to replace cations in 3D perovskite with spacer molecules to form Ruddlesden-Popper (RP) perovskite, which reduces the connectivity of octahedral network. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Although the bandgap can be broadened by reducing the number of lead layers, adding more organic ligands will hinder carrier transport. In addition, it is difficult to produce stable LHP with single layer thickness by using the current synthesis route, because pure single layer LHP is the easiest to aggregate.…”

All-inorganic perovskite quantum dot light-emitting memories

“…1d ). These results suggest the transfer of Cs + , Pb 2+ , and Br – ions from the soluble to insoluble solvents is too fast during the supersaturated recrystallization process, which significantly enlarges the QD size to ~50–100 nm, larger than the CsPbBr 3 QDs synthesized by the hot-injection method that generally have a smaller size of ~ 10–15 nm 14 , 15 . Nevertheless, the well-resolved lattice fringes with an average interplanar space of 0.59 nm can be observed (Fig.…”

“…To date, all-inorganic metal halide perovskite materials, usually expressed as the chemical formula of ABX 3 , where A and B are metal cations with different sizes and X being a halide anion, have been intensively investigated due to their unique photophysical characteristics and high stability in the ambient environment 14 , 15 . They can be easily processed by solution methods and be implemented in low-cost, mass-production of optoelectronic devices for high-scalable applications.…”

All-inorganic perovskite quantum dot light-emitting memories

“…QDs synthesized by the hot-injection method that generally have a smaller size of ~ 10 -15 nm 14,15 . Nevertheless, the wellresolved lattice fringes with an average interplanar space of 0.59 nm can be observed ( Fig.…”