Preparation and fluorescence properties of SiO₂-coated CsPb_1−xZn _xBr₃ nanocrystals with enhanced efficiency and stability

Abstract

All-inorganic perovskite CsPbX₃ (X = Cl, Br, I) nanocrystals (NCs) have emerged as promising candidates for light-emitting diode (LED) displays due to their outstanding photophysical properties. However, their practical application remains hindered by poor stability and the inherent toxicity of Pb²⁺. In this study, we present a two-step heating method to synthesize CsPb_1−xZn _xBr₃ NCs with enhanced optoelectronic performance and uniform dispersion. The optimized Zn²⁺-doped NCs achieve a photoluminescence quantum yield (PLQY) of 86%, with a reduction in lattice spacing from 0.384 to 0.365 nm, attributed to increased perovskite lattice formation energy and effective surface passivation. To further improve stability, a silica (SiO₂) shell is introduced via surface modification with (3-aminopropyl) triethoxysilane (APTES), forming CsPb_0.7Zn_0.3Br₃@SiO₂ core–shell NCs. At an optimal APTES/B-site metal ion molar ratio of 1.8, the PLQY increases to 96%. The SiO₂ encapsulation significantly enhances environmental stability, with coated NCs retaining 43% of their initial photoluminescence (PL) intensity after immersion in water for 36 h, compared to only 5% for uncoated NCs. Furthermore, after ethanol treatment for 210 min, the coated NCs retain 39% of their initial PL intensity, while the uncoated counterparts retain merely 7%. The enhanced stability and luminescence performance of CsPb_0.7Zn_0.3Br₃@SiO₂ NCs make them highly promising for LED applications. White light-emitting diodes (WLEDs) fabricated using these NCs exhibit a color rendering index (CRI) of 78.2, a correlated color temperature (CCT) of 5470 K, and a luminous efficiency (LE) of 54.2 lm/W, demonstrating significant potential for next-generation display and lighting technologies.

Keywords

CsPbX₃ nanocrystals / zinc ion doping / silica-coated / white light-emitting diode / stability

References

[1] ChouhanL, GhimireS, SubrahmanyamC, MiyasakaT, BijuV. Synthesis, optoelectronic properties and applications of halide perovskites. Chem. Soc. Rev., 2020, 49(10): 2869

[2] J. Chen, C. Zhang, X.L. Liu, L. Peng, J. Lin, and X.F. Chen, Carrier dynamic process in all-inorganic halide perovskites explored by photoluminescence spectra, Photon. Res., 9(2021), No. 2, art. No. 151.

[3] T. Chiba, S. Ishikawa, J. Sato, et al., Blue perovskite nanocrystal light-emitting devices via the ligand exchange with adamantane diamine, Adv. Opt. Mater., 8(2020), No. 13, art. No. 2000289.

[4] L. Chen, Y. Chu, X.X. Qin, et al., Ultrafast dynamics across pressure-induced electronic state transitions, fluorescence quenching, and bandgap evolution in CsPbBr₃ quantum dots, Adv. Sci., 11(2024), No. 14, art. No. 2308016.

[5] J.H. Sun, Z.D. Zhang, Y.Y. Chen, et al., Quantum-defect-minimized, three-photon-pumped ultralow-threshold perovskite excitonic lasing, Adv. Funct. Mater., 34(2024), No. 30, art. No. 2401247.

[6] ZhangX, TangYQ, LinF, YeSY, LiY. High color purity CsPbBr₃ nanocrystals prepared by a heterogeneous reaction system. ACS Appl. Nano Mater., 2024, 7(7): 7812

[7] Z. Liu, W.D. Qiu, X.M. Peng, et al, Perovskite light-emitting diodes with EQE exceeding 28% through a synergetic dual-additive strategy for defect passivation and nanostructure regulation, Adv. Mater., 33(2021), No. 43, art. No. 2103268.

[8] Y.H. Geng, J.Z. Guo, H.Q. Wang, et al., Large-scale production of ligand-engineered robust lead halide perovskite nanocrystals by a droplet-based microreactor system, Small, 18(2022), No. 19, art. No. 2200740.

[9] S. Song, W.Z. Wang, and B.Q. Cao, Single silica-coated CsPb-Br₃ perovskite quantum dots with enhanced stability and excellent optical properties, Opt. Mater., 133(2022), art. No. 113070.

[10] S.Q. Sun, M. Lu, J. Guo, et al., ZnBr₂ mediated transformation from nonluminescent Cs₄PbBr₆ to green-emitting Zn-doped CsPbBr₃/Cs₄PbBr₆ nanocrystals for electroluminescent light-emitting diodes, Chem. Eng. J., 433(2022), art. No. 133556.

[11] K.M. Cui, Y.Q. Wen, X.Y. Han, Z.B. Hao, J.H. Zhang, and J. Xie, Intense blue emission from one-pot synthesized quaternary CsZn_xPb_1−xBr₃ perovskite quantum dots, Opt. Mater., 136(2023), art. No. 113441.

[12] M.D. Jin, X.Y. Zhai, Y.K. Huang, et al., Biocompatible silica-coated europium-doped CsPbBr₃ nanoparticles with luminescence in water for zebrafish bioimaging, Small, 20(2024), No. 26, art. No. 2310238.

[13] ZhaoWG, YangD, YangZ, LiuSZ. Zn-doping for reduced hysteresis and improved performance of methylammonium lead iodide perovskite hybrid solar cells. Mater. Today Energy, 2017, 5: 205

[14] Y.T. Zeng, Z.R. Li, S.P. Chang, A. Ansay, Z.H. Wang, and C.Y. Huang, Bright CsPbBr₃ perovskite nanocrystals with improved stability by in situ Zn-doping, Nanomaterials, 12(2022), No. 5, art. No. 759.

[15] R.J. Chen, Y. Xu, S. Wang, et al., Zinc ions doped cesium lead bromide perovskite nanocrystals with enhanced efficiency and stability for white light-emitting diodes, J. Alloy. Compd., 866(2021), art. No. 158969.

[16] X.W. Zhou, Y. Zhao, W.Z. Huang, Y.Y. Wu, Z.E. Wu, and G.F. He, Enhanced performance of inverted CsPbBr₃ nanocrystal LEDs via Zn(II) doping, Org. Electron., 96(2021), art. No. 106253.

[17] JiX, LuR, YuAC. Insight into the structures and photophysics of Zn-alloyed lead bromide perovskite nanocrystals synthesized by a post-ion-exchange method and a one-pot hot injection method. J. Phys. Chem. C, 2024, 128(16): 6735

[18] ShenXY, ZhangY, KershawSV, et al.. Zn-alloyed CsPbI₃ nanocrystals for highly efficient perovskite light-emitting devices. Nano Lett., 2019, 19(3): 1552

[19] SongL, ZhangQ, UllahS, LiuKN, LiuYX, DaiJ. Improved exciton photoluminescence of Zn-doped quasi-2D perovskite nanocrystals and their application as luminescent materials in light-emitting devices. J. Mater. Chem. C, 2023, 11(13): 4526

[20] T. Chen, Y.H. Chen, Y.P. Li, M.B. Liang, W.K. Wu, and Y.D. Wang, A review on multiple I–III–VI quantum dots: Preparation and enhanced luminescence properties, Materials, 16(2023), No. 14, art. No. 5039.

[21] T. Chen, Y.H. Chen, C.X. Guo, et al., One-step synthesis of nontoxic Ag-In-Zn-S quantum dots via microwave-assisted hydrothermal method for bioimaging, J. Mol. Struct., 1296(2024), art. No. 136928.

[22] WangP, WuZH, WuMY, WeiJ, SunYN, ZhaoZF. All-solution-processed, highly efficient and stable green light-emitting devices based on Zn-doped CsPbBr₃/ZnS heterojunction quantum dots. J. Mater. Sci., 2021, 56(6): 4161

[23] R. Salari, M. Amjadi, and T. Hallaj, A smartphone-assisted fluorescent sensing platform for ochratoxin A using Mn-doped CsPbBr₃ perovskite quantum dots embedded in the mesoporous silica as a ratiometric probe, Spectrochim. Acta Part A, 312(2024), art. No. 124083.

[24] ZhangS, YuanLF, LiuHL, et al.. Tunable white light-emitting devices based on unilaminar high-efficiency Zn²⁺-doped blue CsPbBr₃ quantum dots. J. Phys. Chem. Lett., 2021, 12(35): 8507

[25] ZhangZ, XuTY, XuK, et al.. Ligand engineering regulation toward Zn ions and Zn substrate for all-climate Zn metal batteries. Angew. Chem. Int. Ed., 2025, 64(14): e202424272

[26] S.N. Liao, M.W. Chen, J. Li, R. Zhang, and Y.P. Yang, High-performance photodetectors based on low-defect CsPb_1−xZn_xBr3 quantum dots, J. Mater. Sci. Mater. Electron., 35(2024), No. 10, art. No. 715.

[27] Z.Y. Yao, Y.L. Yin, Y. Xia, and H.T. Chen, Unique luminescence properties in Zn²⁺-doped CsPbBr3 perovskite nanocrystals, Nano, 17(2022), No. 10, art. No. 2250078.

[28] L. Ding, C.Y. Shen, Y. Zhao, et al., CsPbBr₃ nanocrystals glass facilitated with Zn ions for photocatalytic hydrogen production via H₂O splitting, Mol. Catal., 483(2020), art. No. 110764.

[29] LiuZQ, ZhangYQ, FanY, et al.. Toward highly luminescent and stabilized silica-coated perovskite quantum dots through simply mixing and stirring under room temperature in air. ACS Appl. Mater. Interfaces, 2018, 10(15): 13053

[30] LuoBB, PuYC, LindleySA, et al.. Organolead halide perovskite nanocrystals: Branched capping ligands control crystal size and stability. Angew. Chem. Int. Ed, 2016, 55(31): 8864

[31] LiM, ZhangX, YangP. Controlling the growth of a SiO₂ coating on hydrophobic CsPbBr₃ nanocrystals towards aqueous transfer and high luminescence. Nanoscale, 2021, 13(6): 3860

[32] KimD, JoYR, KimS, YimSY, LeeJH, LeeCL. Investigation of potassium doping and defect healing mechanism in core-shell CsPbBr₃/SiO₂ quantum dots. J. Mater. Chem. C, 2024, 12(18): 6395

[33] WangSS, DuL, JinZC, XinY, MattoussiH. Enhanced stabilization and easy phase transfer of CsPbBr₃ perovskite quantum dots promoted by high-affinity polyzwitterionic ligands. J. Am. Chem. Soc., 2020, 142(29): 12669

[34] WangB, ZhangS, LiuB, LiJK, CaoBQ, LiuZM. Stable CsPbBr₃:Sn@SiO₂ and Cs₄PbBr₆:Sn@SiO₂ core–shell quantum dots with tunable color emission for light-emitting diodes. ACS Appl. Nano Mater., 2020, 3(3): 3019

[35] H.Y. Dong, S.Y. Tian, X.J. Sun, et al., High green purity and narrow emission ceramic-like perovskite nanocrystals enabled by solid-phase reaction process, Adv. Opt. Mater., 11(2023), No. 17, art. No. 2300309.

[36] SunJM, LuZT, LiuY, et al.. A highly stable CsPbBr₃–SiO₂ glass ceramic film sintered on a sapphire plate for laser-driven projection displays. J. Mater. Chem. C, 2022, 10(45): 17109

[37] WangT, WeiX, ZongYH, ZhangS, GuanWS. An efficient and stable fluorescent sensor based on APTES-functionalized CsPbBr₃ perovskite quantum dots for ultrasensitive tetracycline detection in ethanol. J. Mater. Chem. C, 2020, 8(35): 12196

[38] X.S. Tang, W.W. Chen, Z.Z. Liu, et al., Ultrathin, core-shell structured SiO₂ coated Mn²⁺-doped perovskite quantum dots for bright white light-emitting diodes, Small, 15(2019), No. 19, art. No. 1900484.

[39] CaoPY, YangBB, ZhengF, WangL, ZouJ. High stability of silica-wrapped CsPbBr₃ perovskite quantum dots for light emitting application. Ceram. Int., 2020, 46(3): 3882

[40] KumarP, PatelM, ParkC, et al.. Highly luminescent biocompatible CsPbBr₃@SiO₂ core-shell nanoprobes for bioimaging and drug delivery. J. Mater. Chem. B, 2020, 8(45): 10337

[41] MengCF, YangDD, WuY, ZhangXJ, ZengHB, LiXM. Synthesis of single CsPbBr₃@SiO₂ core-shell particles via surface activation. J. Mater. Chem. C, 2020, 8(48): 17403

[42] PanAZ, WuYS, YanK, et al.. Stable luminous nanocomposites of confined Mn²⁺-doped lead halide perovskite nanocrystals in mesoporous silica nanospheres as orange fluorophores. Inorg. Chem., 2019, 58(6): 3950

[43] DongYT, WangYK, YuanFL, et al.. Bipolar-shell resurfacing for blue LEDs based on strongly confined perovskite quantum dots. Nat. Nanotechnol., 2020, 15(8): 668

[44] PengY, MouY, WangT, et al.. Effective heat dissipation of QD-based WLEDs by stacking QD film on heat-conducting phosphor-sapphire composite. IEEE Trans. Electron Devices, 2019, 66(6): 2637

RIGHTS & PERMISSIONS

University of Science and Technology Beijing

Just Accepted

This article has successfully passed peer review and final editorial review, and will soon enter typesetting, proofreading and other publishing processes. The currently displayed version is the accepted final manuscript. The officially published version will be updated with format, DOI and citation information upon launch. We recommend that you pay attention to subsequent journal notifications and preferentially cite the officially published version. Thank you for your support and cooperation.