Tunable Luminescence and Enhanced Polar Solvent Resistance of Perovskite Nanocrystals Achieved by Surface-Initiated Photopolymerization

Abstract

Colloidal lead halide perovskite nanocrystals (PNCs) have demonstrated great potential as materials of light-emitting diodes if their colloidal and compositional instability could be addressed. Herein, we reported a facile surface-initiated photopolymerization method that introduced polymers on a CsPbBr3 PNC surface to achieve improved stability and regulated halide exchange of PNCs in polar solvents. Synthetic polymers grafted from the surface of an individual PNC surface stabilized the PNCs, in which the multidentate linkage initiators and the extending polymers were two essential factors. The polymer-grafted PNCs showed composition-dependent colloidal dispersity and structural stability in various polar organic solvents and aqueous condition. It was found that changing the polarity of dispersing solvents effectively switched the swelling and collapsed states of surface polymers on the PNC–polymer nanoparticles, which provided an on–off mechanism to regulate the permeation of halide anions into the PNC cores. Thus, halide exchange of polymer-grafted PNCs in a good solvent for polymers varied the composition of PNCs and their emissive color, while switching the nanoparticles into a poor solvent, for example, ethanol and water, collapsed the surface polymer, prohibited the halide exchange, and consequently retained the color stability. It was demonstrated that different CsPbX3 PNCs with collapsed surface polymers could coexist into one solvent medium, achieving simultaneous emission with a white display. We believe this work provided insights into the rational functionalization of PNC materials using well-defined synthetic polymers toward tunable emission and outstanding stability in polar media.

Polar-Solvent-Free Sonochemical Synthesis of Mn(II)-Doped CsPbCl3 Perovskite Nanocrystals for Dual-Color Emission

“…1−6 Due to these excellent optical and transport properties, metal-halide perovskites have been extensively used in constructing photovoltaic materials, such as low-threshold lasers, 7 highefficiency solar cells, 8 light-emitting diodes (LEDs) and anticounterfeiting, 9,10 and ultrafast photodetectors. 11 To date, the most commonly adopted approaches for synthesizing PNCs are hot-injection (H-I), 1,12 sonochemical, 3,14 anionexchange methods, 15,16 solvothermal, 17,18 room temperaturebased ligand-assisted reprecipitation (LARP), 19,20 and super-saturated recrystallization (SR), 21,22 in which particle shape and size are tuned by controlling the precursor composition, temperature, and reaction time. Notably, the H-I method is the most widely used method for synthesizing high-quality MHPNCs; however, the synthesis of PNCs by this method requires pre-synthesized precursors, high temperature, vacuum, and inert atmospheres and has low yield and high cost.…”

“…Metal halide perovskite nanocrystals (MHPNCs) of generalized formula ABX 3 (A = Cs, Rb, CH 3 NH 3 , and CH­(NH 2 ) 2 ; B = Pb, Sn, and Ge; X = Cl, Cl/Br, Br, Br/I, and I) have emerged as a new class of semiconducting materials owing to their solution processability for cost-effective synthesis and outstanding photophysical properties, such as tunable bandgaps, narrow-band emissions, structure dimensionality (0D to 3D), defect tolerance, low trap densities, long charge carrier mobilities, long minority carrier diffusion lengths, and near-unity photoluminescence quantum yields (PLQYs). − Due to these excellent optical and transport properties, metal-halide perovskites have been extensively used in constructing photovoltaic materials, such as low-threshold lasers, high-efficiency solar cells, light-emitting diodes (LEDs) and anticounterfeiting, , and ultrafast photodetectors . To date, the most commonly adopted approaches for synthesizing PNCs are hot-injection (H-I), , sonochemical, , anion-exchange methods, , solvothermal, , room temperature-based ligand-assisted reprecipitation (LARP), , and supersaturated recrystallization (SR), , in which particle shape and size are tuned by controlling the precursor composition, temperature, and reaction time. Notably, the H-I method is the most widely used method for synthesizing high-quality MHPNCs; however, the synthesis of PNCs by this method requires pre-synthesized precursors, high temperature, vacuum, and inert atmospheres and has low yield and high cost.…”

Tiny spots to light the future: advances in synthesis, properties, and application of perovskite nanocrystals in solar cells

“…92 Post-patterning anion exchange with iodide salts converts CsPbBr 3 NCs to CsPbI 3− x Br x patterns and suggests that the PNC cores remain reactive and accessible probably due to the low degree of cross-linking, in contrast to cross-linked ligands via X-ray irradiation or with polymeric ligands. 93–95 Furthermore, the method shows the preservation of optical absorption and emission characteristics before and after cross-linking at mild conditions 92 without a high-energy source or a ligand exchange process. UV irradiation has promoted crosslinking reactions between PNCs using a polymer backbone containing a cinnamoyl group 95 or 2,2-dimethoxy-2-phenylacetophenone (DMPA).…”

Shape-controlled synthesis of one-dimensional cesium lead halide perovskite nanocrystals: methods and advances

“…The PL wavelength of the CsPbX 3 NCs can be tuned by halide composition control. [106][107][108][109] The chloride NCs show blueshifted emission, while the iodide NCs give red-shifted emission. There are two ways to obtain 1D Cl or I derivatives.…”