Ultrasmall CsPbBr₃ Quantum Dots with Bright and Wide Blue Emissions

Abstract

Low-dimensional metal halide perovskites have been widely regarded due to their unique crystal structure and photophysical properties. Herein, blue-emission CsPbBr 3 quantum dots (QDs) or nanocrystals (NCs) with extremely small crystal size (1-2 nm) but high photoluminescence quantum yield (PLQY, 72.4%) are synthesized with a new surface ligand, single (6-amino-6-deoxy) beta cyclodextrin (6A-βCD), which also acts as the confined-growth template for such small QDs. Detailed photoluminescence spectrum and femtosecond transient absorption spectrum study proves that the blue emission with multiple peaks originates from both band-edge radiation and exciton recombination. Furthermore, as a result of the small size, exciton localization in the form of self-trapped excitons (STEs) and significant quantum size confinement effect are both important reasons for the efficient and wide blue emissions of these QDs. This work provides a new strategy not only to synthesize ultrasmall perovskite QDs but also to develop blue perovskite-QD light-emitting devices.

Water‐induced CsBr crystalline transition to CsPbBr3 and the change of luminescence properties in borophosphate glass

“…Under the 365‐nm UV lamp, the PL color changed from blue to cyan for 5‐min water treatment and to green for 10‐min water treatment. The blue light is instinctively believed to be the luminescence of the pony‐size CsPbBr 3 NCs 27,28 . To determine the source of the blue light emission from the glass, Ag Kα XRD analysis was performed on BP1, which was different from Cu Kα XRD.…”

“…The blue light is instinctively believed to be the luminescence of the pony-size CsPbBr 3 NCs. 27,28 To determine the source of the blue light emission from the glass, Ag Kα XRD analysis was performed on BP1, which was different from Cu Kα XRD. Ag Kα XRD needs to place the powder sample in a slender glass tube at 29 The absorption spectrum shows that the absorption edge is about 400 nm.…”

Biomolecules incorporated in halide perovskite nanocrystals: synthesis, optical properties, and applications

“…Beyond acting as surface passivating agents, CDs have also been used as templates to modulate the size of HPNCs during synthesis. 101 Ultrasmall CsPbBr 3 NCs (1–2 nm) with bright and wide blue emissions and PLQY of 72.4% were synthesized using (6-amino-6-deoxy)-β-cyclodextrin (6A-β-CD) to restrict the growth of HPNCs to the width of the CD cavity. 101 There were no variations on the size and morphology of NCs when the concentration of 6A-β-CD was altered; this suggests the growth of the NPs is restricted to the intrinsic size of the cavity, confirming that 6A-β-CD is acting as a template.…”

Stable Blue-Emitting CsPbBr3 Nanoplatelets for Lighting and Display Applications

“…Generally, there are three synthetic routes for the preparation of pure blue emissive all-inorganic perovskites: (i) adjusting the composition of halogen, (ii) reducing the grain size to obtain CsPbBr 3 NCs with an extremely small size­(<5 nm), and (iii) modulating the quantum-well structure to achieve 2-dimensional (2D) CsPbBr 3 NPLs. − Among them, the last route can avoid the lattice mismatch and phase separation common in the first route and overcome the broad emission bands caused by ultrafast nucleation and growth in the second route. − In addition, 2D CsPbBr 3 NPLs with a strong quantum confinement effect can increase the exciton binding energy, which is beneficial to efficient blue light emission. − However, the development of standard pure blue-emitting CsPbBr 3 NPLs remains a great challenge. Dynamic and weak binding between conventional ligands (OAm and OA) and CsPbBr 3 NPL surfaces often leads to surface vacancy defects and subsequent nonradiative recombination processes, , resulting in deteriorating optical properties and stability. − Therefore, light- and temperature-driven particle growth, polar solution-triggered NPLs destabilization, and subsequent loss of quantum confinement are often observed in both dispersion and thin films. − …”