鹵化物鈣鈦礦因具有可調控能隙、高吸收係數、高發光效率與低雷射閾值等優點，近年來受到廣泛關注。其中，全無機 CsPbX₃（X = Cl, Br, I）鈣鈦礦可透過鹵素比例調控發光波長，成為可調控雷射材料的重要候選者。然而，目前針對大面積、高品質且組成可精細調控之混鹵鈣鈦礦磊晶薄膜研究仍相對有限，特別是在短波長雷射與激子相關光學特性方面仍有探討空間。
本研究利用三區溫控化學氣相沉積法成長 CsPbBr₃ 磊晶薄膜，並透過結構與光學量測確認其具有良好的結晶品質與發光特性。接著，為實現能隙與發光波長調控，進一步嘗試液相離子置換法進行鹵素交換。結果顯示，液相離子置換可快速改變薄膜發光波長，但同時存在置換不完全、發光不均勻與光強度下降等問題，限制其在高品質可調控雷射薄膜上的應用。
因此，本研究進一步發展四元前驅物粉末合成方法，利用 CsCl、CsBr、PbCl₂ 與 PbBr₂ 作為來源材料，合成不同 Cl/Br 比例之 CsPbCl3(1−x)Br3x 混鹵鈣鈦礦前驅物，並結合 mica 基板進行大面積磊晶薄膜成長。光學顯微與元素分析結果顯示，所製備薄膜具有良好的大面積覆蓋性與組成均勻性。X 光繞射分析顯示，隨著 Br 含量增加，繞射峰逐漸往低角度位移，代表晶格因 Br⁻ 取代 Cl⁻ 而產生系統性膨脹。
在光學特性方面，吸收與光激發螢光光譜顯示CsPbCl3(1−x)Br3x薄膜之能隙可隨 Br 含量增加由約 3.10 eV 調降至 2.43 eV，證明本研究可有效實現能隙與發光波長調控。此外，Cl-rich 組成薄膜展現明顯的激子吸收特徵，顯示其具有良好的光學品質與短波長雷射應用潛力。綜合上述結果，本研究成功建立大面積、組成可調且具良好光學特性之CsPbCl3(1−x)Br3x 混鹵鈣鈦礦磊晶薄膜製程，可作為未來可調控雷射與極化子雷射應用之材料平台。

Halide perovskites have attracted extensive attention in recent years due to their tunable bandgap, high absorption coefficient, high photoluminescence efficiency, and low lasing threshold. Among them, all-inorganic CsPbX₃ (X = Cl, Br, I) perovskites can tune their emission wavelength through halide composition control, making them promising candidates for tunable laser applications. However, studies on large-area, high-quality mixed-halide perovskite epitaxial films with fine composition tunability remain limited, especially for short-wavelength lasers and exciton-related optical properties.
In this study, CsPbBr₃ epitaxial films were first grown using a three-zone chemical vapor deposition system, and their good crystalline quality and optical properties were confirmed through structural and optical characterizations. To further achieve bandgap and emission wavelength tuning, liquid-phase ion exchange was carried out for halide substitution. The results show that liquid-phase ion exchange can rapidly change the emission wavelength of the films; however, incomplete exchange, nonuniform emission, and reduced photoluminescence intensity limit its application in high-quality tunable laser films.
Therefore, a quaternary precursor powder synthesis method was further developed in this work. CsCl, CsBr, PbCl₂, and PbBr₂ were used as source materials to synthesize CsPbCl3(1−x)Br3x mixed-halide perovskite precursors with different Cl/Br ratios, followed by large-area epitaxial film growth on mica substrates. Optical microscopy and elemental analysis results show that the prepared films exhibit good large-area coverage and compositional uniformity. X-ray diffraction analysis reveals that the diffraction peaks gradually shift toward lower angles with increasing Br content, indicating systematic lattice expansion caused by the substitution of Cl⁻ with Br⁻.

For the optical properties, absorption and photoluminescence spectra show that the bandgap of the CsPbCl3(1−x)Br3x films can be tuned from approximately 3.10 eV to 2.43 eV with increasing Br content, demonstrating effective control of bandgap and emission wavelength. In addition, the Cl-rich films exhibit pronounced excitonic absorption features, indicating good optical quality and potential for short-wavelength laser applications. Overall, this study successfully establishes a large-area, composition-tunable CsPbCl3(1−x)Br3x mixed-halide perovskite epitaxial film process with good optical properties, providing a promising material platform for future tunable lasers and polariton laser applications.

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