Tuning the Optical Properties of Cesium Lead Halide Perovskite Nanocrystals by Anion Exchange Reactions

Abstract

We demonstrate that, via controlled anion exchange reactions using a range of different halide precursors, we can finely tune the chemical composition and the optical properties of presynthesized colloidal cesium lead halide perovskite nanocrystals (NCs), from green emitting CsPbBr3 to bright emitters in any other region of the visible spectrum, and back, by displacement of Cl– or I– ions and reinsertion of Br– ions. This approach gives access to perovskite semiconductor NCs with both structural and optical qualities comparable to those of directly synthesized NCs. We also show that anion exchange is a dynamic process that takes place in solution between NCs. Therefore, by mixing solutions containing perovskite NCs emitting in different spectral ranges (due to different halide compositions) their mutual fast exchange dynamics leads to homogenization in their composition, resulting in NCs emitting in a narrow spectral region that is intermediate between those of the parent nanoparticles.

Colloidal lead halide perovskite nanocrystals: synthesis, optical properties and applications

“…Kovalenko and colleagues 68 and Manna and colleagues 69 have almost simultaneously reported this approach for CsPbX 3 (X = Cl, Br, I) NC systems, tuning their emission over the spectral range of 410 − 700 nm with high PLQYs of 20 − 80% (Figures 5a and b). Such anion exchange was also reported for hybrid MAPbBr 3 NCs, which were synthesized in an approach similar to that of Pérez-Prieto and colleagues, 30 and subsequently mixed with methyl ammonium halide (Cl or I) to produce MAPbBr 3 − x Cl x or MAPbBr 3 − x I x NCs (Figure 5c).…”

Aluminum‐Doped Cesium Lead Bromide Perovskite Nanocrystals with Stable Blue Photoluminescence Used for Display Backlight

“…For light emitting application, doping of lead cation site maybe more effective in the band engineering than doping of mono‐valent cation site because the upper valence band is formed predominately by the halide p‐orbitals and the lower conduction band is formed by the overlap of the lead p‐orbitals. For example, cation substitutions of CsPbBr 3 NCs with CH 3 NH 3 + resulted in a peak emission shift from 510.2 to 525.4 nm, similar to that of CH 3 NH 3 PbBr 3 (527 nm) 9. For lead cation site, in both bulk and nanocrystalline forms, color‐tuning by partial lead substitution during the synthesis has been proven successful.…”

Polymer-Enhanced Stability of Inorganic Perovskite Nanocrystals and Their Application in Color Conversion LEDs

“…2,[5][6][7] Compared to classical Cd-based chalcogenide quantum dots (QDs), CsPbX 3 (X = Cl, Br, I) offer a very broad and easily adjustable composition versatility together with ample options for shape control, which allow tuning of their emission wavelength throughout the whole visible spectrum. [8][9][10][11][12][13][14] Among other applications, such highly luminescent and spectrally tunable NCs are ideally suited to produce monochromatic and white LEDs (WLEDs). 15 In this regard, CsPbX 3 NCs have been utilized as the emissive layer in electroluminescent monochromatic and color conversion QD-LEDs showing exceptionally narrow emission bandwidths and thus high color quality in devices.…”