| 摘要: | 近來隨著顯示技術的快速發展，穿戴式裝置與可折疊電子產品需求日漸增加，相較於傳統的玻璃基板的先天限制，軟性基板因具備機械可撓性與輕薄之特性，成為次世代光電元件的關鍵材料。鑒於聚對苯二甲酸乙二酯（Polyethylene Terephthalate, PET）雖廣泛應用於軟性基板鈣鈦礦發光二極體(Perovskite Light-Emitting Diodes, PeLEDs)中，但其玻璃轉移溫度與熱穩定性較低，無法導入高溫製程，使得相關電子元件中主動層的結晶品質與穩定性不佳，因而影響耐用性與可靠度。綜上所述，本研究採具有較高耐熱性的聚萘二甲酸乙二酯（Polyethylene Naphthalate, PEN）作為元件基板，以期改善相關元件的鈣鈦礦薄膜品質與穩定性。
本研究採用真空熱蒸鍍（Thermal evaporation）方式製備發光層，並以氧化鋅（Zinc Oxide, ZnO）作為電子傳輸層（Electron Transport Layer, ETL），主要因其適當的導帶能階能與鈣鈦礦主動層形成良好能階對位，可有效促進電子注入並抑制電洞往陰極擴散，提高載子覆蓋率與元件效率。為進一步強化載子復合區域，本研究引入 CsBr 與 CsPbBr₃ 交錯堆疊形成的類量子井（Multiple-Quantum Well, MQW）結構，藉由精準調控單層厚度與組數，實現發光區域的空間侷限與載流子遷移調控。透過製程中對相關元件進行熱處理，進一步促進薄膜結晶性並降低缺陷密度。
在光學特性方面，利用紫外可見光吸收光譜（Ultraviolet visible spectroscopy, UV-vis）觀察發光層光學性能變化，並輔以 X 光繞射（X-ray Diffraction, XRD）分析結晶性改變。最後在電性方面，透過四點探針量測獲得不同結構下的相關電特性。
本研究以 ITO 為導電陰極、C 為陽極材料組成 PEN / ITO / ZnO / CsPbBr₃ / C 的元件結構，此元件於操作電壓 2.8 V 下可達到 1176 nits 的峰值輝度，顯示MQW結構在提升發光效率與均勻性方面的潛力。
;With the rapid advancement of display technology, the demand for wearable and foldable electronic devices has been steadily increasing. Compared to the inherent limitations of traditional glass substrates, flexible substrates, due to their mechanical bendability and lightweight characteristics, have become key materials for next-generation optoelectronic devices. Although polyethylene terephthalate (PET) is widely used in flexible perovskite light-emitting diodes (PeLEDs), its relatively low glass transition temperature and poor thermal stability prevent the use of high-temperature processes. This limitation leads to suboptimal crystallinity and stability in the active layer, ultimately affecting device durability and reliability. To address this issue, this study adopts polyethylene naphthalate (PEN) as the substrate, owing to its superior heat resistance, aiming to improve the film quality and stability of perovskite layers in related devices.
In this work, the emission layer was fabricated via thermal vacuum evaporation, and zinc oxide (ZnO) was selected as the electron transport layer (ETL) due to its suitable conduction band level, which enables favorable energy-level alignment with the perovskite active layer. This configuration facilitates efficient electron injection, suppresses hole diffusion toward the cathode, increases carrier confinement, and enhances overall device performance. To further improve charge recombination, a multiple-quantum well (MQW) structure composed of alternating layers of CsBr and CsPbBr₃ was introduced. By precisely controlling the thickness and repetition number of each layer, spatial confinement of the emission zone and regulation of carrier transport were effectively achieved. Post-deposition thermal treatment was applied to promote crystallization and reduce defect density within the perovskite films.
For optical characterization, ultraviolet-visible (UV-vis) spectroscopy was used to monitor changes in the optical properties of the emission layer, complemented by X-ray diffraction (XRD) to evaluate crystallinity variations. In terms of electrical performance, four-point probe measurements were conducted to analyze the electrical characteristics under different structural conditions.
The final device architecture comprised PEN/ITO/ZnO/CsPbBr₃/C, using ITO as the cathode and carbon as the anode. This device achieved a peak luminance of 1176 nits at an operating voltage of 2.8 V, corresponding to a structure consisting of two pairs of alternating CsBr + CsPbBr₃ layers with a total thickness of approximately 200 nm demonstrating the potential of the MQW structure in enhancing emission efficiency and uniformity. |
