Postsynthetic Surface-Treatment of CsPbX₃ (X = Cl, Br, or I) Nanocrystals via CdX₂ Precursor Solution toward High Photoluminescence Quantum Yield

Abstract

The existing defects on the surface of CsPbX3 nanocrystals (NCs) resulted in the decrease of the photoluminescence quantum yields (PLQYs) of NCs. In this study, we developed a simple strategy, which can make the treated CsPbX3 NCs exhibit high PLQYs and better stability by CdX2 post-treatment at room temperature. The treated CsPbX3 NCs were characterized by X-ray diffraction (XRD) patterns and PL spectra. The shape, size, and crystal structure of the NCs remained unchanged after Cd ion treatment. The PLQYs of CsPbCl3 increased from 24 to 73% and the PLQYs of CsPbBr3 NCs increased from 85 to 92% after treatment. The significant enhancement of PLQYs is ascribed to the effective passivation of surface defects, in which Cd2+ and X– ions occupied the Pb–X vacancies existing on the surface of the NCs. In addition, this strategy was also applied to a mixed halide perovskite. The practical application of CsPbX3 NCs will be extended by this method.

Enhanced Photoluminescence Quantum Yield, Lifetime, and Photodetector Responsivity of CsPbBr3 Quantum Dots via Antimony Tribromide Post-Treatment

“…A blue shift occurred immediately due to Cl − anion exchange and halide defect passivation. 40 After 24 h of analysis, there is a significant enhancement in the PLQY; also, peaks were red-shifted due to slow diffusion and the doping of Sb 3+ . 46 Further, the higher-concentration SbCl 3 post-treated PL peak exhibits a blue shift due to the Cl − anion exchange, and after 24 h, the higherquantity Sb(III) completely replaces Pb (II), and it could be transformed into a two-dimensional (2D) perovskite structure (Figure S3).…”

“…8 The smaller-size metal cations could be diffused and accommodated on the surface of CsPbX 3 QDs during the postsynthesis treatment process, which enhances the stability and PLQY. 40 Particularly divalent metal halides were extensively employed in the postsynthesis surface treatment process to increase PLQY and the stability of CsPbX 3 quantum dots. Mainly, Di Stasio et al reported the enhancement of room-temperature-synthesized CsPbBr 3 QDs PLQY from 54 to 83% using PbBr 2 post-treatment.…”

“…41 Likewise, Xie et al used CdX 2 for postsynthesis surface treatment to improve PLQY and the optical stability of CsPbX 3 QDs through simultaneous Cd 2+ and Br − surface passivation without modifying the CsPbX 3 crystal structure. 40 Moreover, the postsynthesis surface treatment process using trivalent metal halides that would enhance the properties of CsPbBr 3 QDs is not yet studied widely to date. In this work, we have reported trivalent SbBr 3 -based post-treatment to improve CsPbBr 3 QD properties and also investigated the effect of post-treatment on photodetector applications.…”

Improved One- and Multiple-Photon Excited Photoluminescence from Cd2+-Doped CsPbBr3 Perovskite NCs

“…As an alternative approach, Mondal and co-workers demonstrated the post-synthetic treatment of CsPbCl 3 NCs with CdCl 2 that resulted in the tremendous growth of PLQY [ 35 ]. Very recently, Xie et al, demonstrated that post-synthetic surface treatment of CsPbBr 3 NCs with CdX 2 precursors enlarged their PLQY from 85% to 92% [ 36 ].…”

Room‐Temperature Direct Synthesis of Tetragonal β‐CsPbI3 Nanocrystals

“…Several techniques have been developed for synthesizing αand γ-CsPbI 3 NCs. [13][14][15][16][17][18][19][20][21] Typically, they can be synthesized through the hot-injection method under inert gas protection, which usually produce NCs with good crystal quality but low synthetic yield, thus is not applicable for low cost massive production. [22] In contrast, the solvent induced reprecipitation at room-temperature (RT) has been demonstrated as a convenient and low-cost route to fabricate CsPbX 3 (X = Cl and/or Br) NCs.…”