全無機銫鉛鹵化物鈣鈦礦量子點有著窄放光線寬、高光致發光量子產率、可調變能隙等優異的光學特性，適合被應用在各種光電元件，例如太陽能電池、光偵測器、發光二極體等。採用熱注入法合成的CsPbBr3量子點，製成簡單、成本低，可在室溫下保存、使用，且可透過調整量子點的成長溫度控制量子點的結晶大小，且量子點的放光受量子侷限效應影響，放光波長會隨尺寸縮小而藍移。本實驗對不同尺寸量子點做Hanbury-Brown and Twiss實驗，觀察強與弱量子侷限量子點的反聚束特性。為了讓量子點尺寸均勻成長，在熱注入過程中加入ZnBr2，能提供充足的Br離子、減少缺陷，達成量子點尺寸均勻性高、製成穩定的效果。
首先，我們對此量子點作材料分析，透過TEM影像觀察到成長溫度從90 ~ 180℃的CsPbBr3量子點，統計各成長溫度量子點的平均尺寸、標準差，並觀察其均勻性，比較有無添加ZnBr2的效果，以能量散射光譜儀分析各結晶形狀的元素比例，找出我們要的CsPbBr3量子點形貌，用X光繞射儀量測觀察量子點的晶相，及其訊號半高寬隨量子點尺寸的寬化。
接著，我們對CsPbBr3量子點做光學特性的量測，從PL和吸收光譜的趨勢可看出能隙隨尺寸的縮小而增加，PL中心波長分布在492 ~ 511 nm，由變強度激發PL的擬合結果判斷，此量子點的發光機制由激子複合所主導，且載子生命週期也有隨尺寸縮小而變短的趨勢。最後，我們對量子點做Hanbury-Brown and Twiss實驗，對光子訊號的二次相干性作分析，會表現出反聚束效應的量子點，代表其具有強量子侷限，反之則為弱量子侷限。

All-inorganic cesium lead halide perovskite quantum dots (QDs) have outstanding optical properties such as narrow emission line width, high photoluminescence quantum yield (PLQY), and tunable bandgap. They are suitable for application in various optoelectronic applications, such as solar cells and photodetectors, light emitting diodes, etc. CsPbBr3 QDs synthesized via the hot-injection method are easy to produce and low cost. They can be stored and operated at room temperature. The crystal size of the QDs can be controlled by adjusting the growth temperature. The photoluminescence wavelength is influenced by the quantum confinement effect, resulting in a blue shift as the QDs size decreases. In this research, we conduct Hanbury-Brown and Twiss (HBT) experiments on QDs of various sizes to observe the anti-bunching characteristics of strong and weak quantum confinement QDs. To ensure uniform growth of QDs, adding ZnBr₂ during the hot injection process supplies sufficient Br ions, reduces defects, and achieves high size uniformity. This approach ensures the stability of the synthesis.
First, we conducted material analysis on the quantum dots. From the Transmission Electron Microscopy (TEM) images, we statistic the average size and standard deviation of the QDs at the growth temperature ranging from 90 ~ 180℃. Observe the size uniformity and compare the effects of adding ZnBr₂. We use Energy Dispersive Spectrometer (EDS) to analyze the element ratio of different crystal shape to find out the morphology of the CsPbBr3 QDs we want. Through X-Ray Diffraction (XRD) measurement, we determined the crystal phase of the QDs and observed the widening of the signal’s full width at half maximum (FWHM) relative to the size of the QDs.
Next, we measured the optical properties of CsPbBr3 QDs. The PL and absorption spectra indicate that the bandgap increases as the size decreases, with the PL wavelength ranging from 492 to 511 nm. According to the fitting results of excitation power-dependent PL measurement, the luminescence mechanism of these QDs is dominated by exciton recombination, and the carrier decay also tends to faster as the size shrinks.
Finally, we conduct Hanbury-Brown and Twiss experiments on QDs to analyze the second-order correlation of photon signals. QDs that exhibit antibunching effects demonstrate strong quantum confinement, while the absence of such effects indicates weak quantum confinement.

[1] C. Zheng, C. Bi, F. Huang, D. Binks, and J. Tian, "Stable and Strong Emission CsPbBr(3) Quantum Dots by Surface Engineering for High-Performance Optoelectronic Films," ACS Appl Mater Interfaces, vol. 11, no. 28, pp. 25410-25416, Jul 17 2019, doi: 10.1021/acsami.9b07818.
[2] L. Liu, A. Najar, K. Wang, M. Du, and S. F. Liu, "Perovskite Quantum Dots in Solar Cells," Adv Sci (Weinh), vol. 9, no. 7, p. e2104577, Mar 2022, doi: 10.1002/advs.202104577.
[3] S. Zhou, R. Tang, and L. Yin, "Slow‐photon‐effect‐induced photoelectrical‐conversion efficiency enhancement for carbon‐quantum‐dot‐sensitized inorganic CsPbBr3 inverse opal perovskite solar cells," Advanced Materials, vol. 29, no. 43, p. 1703682, 2017.
[4] A. Kojima, K. Teshima, Y. Shirai, and T. Miyasaka, "Organometal halide perovskites as visible-light sensitizers for photovoltaic cells," Journal of the american chemical society, vol. 131, no. 17, pp. 6050-6051, 2009.
[5] X. Du et al., "High-quality CsPbBr 3 perovskite nanocrystals for quantum dot light-emitting diodes," RSC advances, vol. 7, no. 17, pp. 10391-10396, 2017.
[6] C. Bi, Z. Yao, X. Sun, X. Wei, J. Wang, and J. Tian, "Perovskite quantum dots with ultralow trap density by acid etching‐driven ligand exchange for high luminance and stable pure‐blue light‐emitting diodes," Advanced Materials, vol. 33, no. 15, p. 2006722, 2021.
[7] W. Zhou et al., "Manipulating ionic behavior with bifunctional additives for efficient sky‐blue perovskite light‐emitting diodes," Advanced Functional Materials, vol. 33, no. 27, p. 2301425, 2023.
[8] J. Song, J. Li, X. Li, L. Xu, Y. Dong, and H. Zeng, "Quantum Dot Light-Emitting Diodes Based on Inorganic Perovskite Cesium Lead Halides (CsPbX3)," Advanced Materials (Deerfield Beach, Fla.), vol. 27, no. 44, pp. 7162-7167, 2015.
[9] K. Chen et al., "Solution‐Processed CsPbBr3 Quantum Dots/Organic Semiconductor Planar Heterojunctions for High‐Performance Photodetectors," Advanced Science, vol. 9, no. 12, p. 2105856, 2022.
[10] H. R. Kim et al., "Cesium Lead Bromide (CsPbBr(3)) Perovskite Quantum Dot-Based Photosensor for Chemiluminescence Immunoassays," ACS Appl Mater Interfaces, vol. 13, no. 25, pp. 29392-29405, Jun 30 2021, doi: 10.1021/acsami.1c08128.
[11] P. Ramasamy, D.-H. Lim, B. Kim, S.-H. Lee, M.-S. Lee, and J.-S. Lee, "All-
62
inorganic cesium lead halide perovskite nanocrystals for photodetector applications," Chemical communications, vol. 52, no. 10, pp. 2067-2070, 2016.
[12] K. Shen et al., "Flexible and self‐powered photodetector arrays based on all‐inorganic CsPbBr3 quantum dots," Advanced Materials, vol. 32, no. 22, p. 2000004, 2020.
[13] M. R. Subramaniam, A. K. Pramod, S. A. Hevia, and S. K. Batabyal, "Enhanced Photoluminescence Quantum Yield, Lifetime, and Photodetector Responsivity of CsPbBr3 Quantum Dots via Antimony Tribromide Post-Treatment," The Journal of Physical Chemistry C, vol. 126, no. 3, pp. 1462-1470, 2022, doi: 10.1021/acs.jpcc.1c07493.
[14] H.-R. Xia, J. Li, W.-T. Sun, and L.-M. Peng, "Organohalide lead perovskite based photodetectors with much enhanced performance," Chemical Communications, vol. 50, no. 89, pp. 13695-13697, 2014.
[15] C. Mi et al., "Biexciton-like Auger Blinking in Strongly Confined CsPbBr(3) Perovskite Quantum Dots," J Phys Chem Lett, vol. 14, no. 23, pp. 5466-5474, Jun 15 2023, doi: 10.1021/acs.jpclett.3c01145.
[16] G. Lubin et al., "Resolving the controversy in biexciton binding energy of cesium lead halide perovskite nanocrystals through heralded single-particle spectroscopy," ACS nano, vol. 15, no. 12, pp. 19581-19587, 2021.
[17] L. Protesescu et al., "Nanocrystals of cesium lead halide perovskites (CsPbX3, X= Cl, Br, and I): novel optoelectronic materials showing bright emission with wide color gamut," Nano letters, vol. 15, no. 6, pp. 3692-3696, 2015.
[18] J. Park, J. Joo, S. G. Kwon, Y. Jang, and T. Hyeon, "Synthesis of monodisperse spherical nanocrystals," Angew Chem Int Ed Engl, vol. 46, no. 25, pp. 4630-60, 2007, doi: 10.1002/anie.200603148.
[19] C. Zhu et al., "Room-Temperature, Highly Pure Single-Photon Sources from All-Inorganic Lead Halide Perovskite Quantum Dots," Nano Lett, vol. 22, no. 9, pp. 3751-3760, May 11 2022, doi: 10.1021/acs.nanolett.2c00756.
[20] S. Paul, G. Kishore, and A. Samanta, "Photoluminescence Blinking of Quantum Confined CsPbBr3 Perovskite Nanocrystals: Influence of Size," The Journal of Physical Chemistry C, vol. 127, no. 21, pp. 10207-10214, 2023, doi: 10.1021/acs.jpcc.3c01336.
[21] H. Igarashi, M. Yamauchi, and S. Masuo, "Correlation between Single-Photon Emission and Size of Cesium Lead Bromide Perovskite Nanocrystals," J Phys Chem Lett, vol. 14, no. 9, pp. 2441-2447, Mar 9 2023, doi: 10.1021/acs.jpclett.3c00059.
[22] B. Wang et al., "Weakly confined organic–inorganic halide perovskite quantum
dots as high-purity room-temperature single photon sources," ACS nano, vol. 18, no. 16, pp. 10807-10817, 2024.
[23] X. Liu, L. Cao, Z. Guo, Y. Li, W. Gao, and L. Zhou, "A review of perovskite photovoltaic materials’ synthesis and applications via chemical vapor deposition method," Materials, vol. 12, no. 20, p. 3304, 2019.
[24] C. K. Møller, "Crystal structure and photoconductivity of caesium plumbohalides," Nature, vol. 182, no. 4647, pp. 1436-1436, 1958.
[25] S. Karim and A. Faissal, "National renewable energy laboratory," in Handbook of Algal Biofuels: Elsevier, 2022, pp. 599-613.
[26] B. Ehrler, E. Alarcón-Lladó, S. W. Tabernig, T. Veeken, E. C. Garnett, and A. Polman, "Photovoltaics Reaching for the Shockley–Queisser Limit," ACS Energy Letters, vol. 5, no. 9, pp. 3029-3033, 2020, doi: 10.1021/acsenergylett.0c01790.
[27] Z. K. Tan et al., "Bright light-emitting diodes based on organometal halide perovskite," Nat Nanotechnol, vol. 9, no. 9, pp. 687-92, Sep 2014, doi: 10.1038/nnano.2014.149.
[28] P. Walter et al., "Early use of PbS nanotechnology for an ancient hair dyeing formula," Nano letters, vol. 6, no. 10, pp. 2215-2219, 2006.
[29] A. I. Ekimov and A. A. Onushchenko, "Quantum size effect in three-dimensional microscopic semiconductor crystals," JETP lett, vol. 34, no. 6, pp. 345-349, 1981.
[30] C. Murray, D. J. Norris, and M. G. Bawendi, "Synthesis and characterization of nearly monodisperse CdE (E= sulfur, selenium, tellurium) semiconductor nanocrystallites," Journal of the American Chemical Society, vol. 115, no. 19, pp. 8706-8715, 1993.
[31] R. H. Brown and R. Q. Twiss, "Correlation between photons in two coherent beams of light," Nature, vol. 177, no. 4497, pp. 27-29, 1956.
[32] A. M. Fox, Quantum optics: an introduction. Oxford University Press, USA, 2006.
[33] M. Fox, Optical properties of solids. Oxford university press, 2010.
[34] K. S. Krane, Modern physics. John Wiley & Sons, 2019.
[35] H. Xia, C. Hu, T. Chen, D. Hu, M. Zhang, and K. Xie, "Advances in conjugated polymer lasers," polymers, vol. 11, no. 3, p. 443, 2019.
[36] K. P. Severin, Energy Dispersive Spectrometry. Springer, 2004.
[37] Y. Dong, T. Qiao, D. Kim, D. Parobek, D. Rossi, and D. H. Son, "Precise Control of Quantum Confinement in Cesium Lead Halide Perovskite Quantum Dots via Thermodynamic Equilibrium," Nano Lett, vol. 18, no. 6, pp. 3716-3722, Jun 13 2018, doi: 10.1021/acs.nanolett.8b00861.
[38] M. C. Brennan, M. Kuno, and S. Rouvimov, "Crystal Structure of Individual CsPbBr(3) Perovskite Nanocubes," Inorg Chem, vol. 58, no. 2, pp. 1555-1560, Jan
22 2019, doi: 10.1021/acs.inorgchem.8b03078.
[39] J. Ye et al., "Strongly-confined colloidal lead-halide perovskite quantum dots: from synthesis to applications," Chemical Society Reviews, 2024.
[40] F. Palazon, Q. A. Akkerman, M. Prato, and L. Manna, "X-ray lithography on perovskite nanocrystals films: from patterning with anion-exchange reactions to enhanced stability in air and water," ACS nano, vol. 10, no. 1, pp. 1224-1230, 2016.
[41] G. Rainò, M. A. Becker, M. I. Bodnarchuk, R. F. Mahrt, M. V. Kovalenko, and T. Stöferle, "Superfluorescence from lead halide perovskite quantum dot superlattices," Nature, vol. 563, no. 7733, pp. 671-675, 2018.