Facet Chemistry and the Impact of Surface Ligands on the Photoluminescence of Different Polyhedral-Shaped CsPbBr₃ Perovskite Nanocrystals

Abstract

Controlling the surface ligand chemistry of lead halide perovskite nanocrystals remains one of the most important parameters for stabilizing different facets and maintaining high photoluminescence quantum yields (PLQYs). Successive washings or the use of antisolvents not only quenches the emission but also changes the crystal phase of these nanocrystals. However, studies to date have mostly focused on oleylammonium ion capped six-faceted hexahedron-shaped halide perovskite nanocrystals. In contrast, herein the impact of other ligands stabilizing other than facets of cube shaped nanocrystals is studied, and the physical insights of interface binding for stabilizing new facets and retaining near-unity PLQYs even with successive washings are discussed. Apart from nanocubes, 12-faceted dodecahedrons and 26-faceted rhombicuboctahedrons of CsPbBr3 having tertiary ammonium ion ligands are explored for successive dilution, precipitation, and redispersion studies with further bromide additions to investigate the change in the PLQY, crystal phase, and optical stability. After comparison, it is established that dodecahedron nanocrystals even in a larger size regime showed robust stability and retained near-unity PLQYs with four successive stages of dilutions and precipitations and hardly showed any differences in low-temperature brightness or any enhancement with extra bromide addition. These results suggest that ligands and facets remain the key features in bringing optical stability to lead halide perovskite nanocrystals.

Size‐ and Temperature‐Dependent Lattice Anisotropy and Structural Distortion in CsPbBr3 Quantum Dots by Reciprocal Space X‐ray Total Scattering Analysis

“…[1][2][3][4][5][6][7][8][9] Their outstanding opto-electronic properties, facile and inexpensive preparation methodsover versatile compositionsand superior photo-or electrically-induced performances have impelled rapid incorporation of LHP NCs into displays and LEDs, and fostered novel applications as solution-grown light and quantum emitters or absorbers. [10,11] Over the past few years, great advances have concerned device optimization and quantum efficiencies, [1,[12][13][14][15] fundamental studies (focusing on the effects of surface chemistry and NCs morphology on the light emissivity and long-term stability), [16] ab-initio calculations (elucidating the origin of LHP defect-tolerant electronic structure and providing the formation energy of defects and justification for their relative abundance), [17][18][19][20][21][22][23][24][25][26][27][28] and a blooming research on collective emissive states (through NC self-assembly into long-range ordered superlattices). [29][30][31][32][33][34][35][36] In all these studies, Lead halide perovskite nanocrystals (NCs) have emerged as next-generation semiconductors capable of unifying superior photoemission properties, facile and inexpensive preparation, compositional and structural versatility.…”

Pt-CsPbBr3 Perovskite Nanocrystal Heterostructures: All Epitaxial

“…Lead halide perovskite nanocrystals are in the forefront of current research because of their efficient light-absorbing and light-emitting properties. − Extensive research has been carried out to understand both the chemistry and physics of these nanocrystals. − ,,− However, in spite of great successes, the reaction pathways leading to epitaxial heterostructures with size-tunable metal particles or other covalent nanocrystals have not yet been deterimined . Even though significant numbers of reports on composites and heterostructures have been reported, ,− targeting one-to-one metal-halide perovskite heterostructures having epitaxial junctions or epitaxial growth of one with selected facets of another has not been successfully established yet .…”

Origin of Excitonic Absorption in Multigrain CsPbBr3 Perovskite Nanocrystals: Implications in Photodiodes

“…The selected area electron diffraction pattern (SAED) shown in Figure h reveals the samples’ crystallinity and monodispersity with the three most intense diffraction rings corresponding to d spacings of 0.57 nm (002), 0.41 nm (020), and 0.28 nm (004). These planes with corresponding d spacing are well matched with the orthorhombic phase of CsPbBr 3 nanocrystals. − The rectangular shape of CsPbBr 3 nanocrystals shown in Figure b having planes (002) and (004) corresponding to d spacings of 0.57 and 0.28 nm was viewed along [001] directions. The HRTEM image shown in Figure d indicates that rectangular-shaped nanocrystals with slight rotation of the [001] axis having a (020) plane (corresponding to a d spacing of 0.41 nm as shown in Figure e) were viewed along the [010] direction.…”