| 摘要: | 為了提升發光元件的演色性，使其於照明應用上有更好的發揮空間，有機和無機半導體材料的結合即提供了具有潛能的選擇。有許多研究也指出有機無機異質介面可擁有兩者材料的特性，使其突破原本單一材料在光性與電性上的限制。本研究揭示了一P型有機(F8T2)/P型(氮化鎵)無機異質介面發光元件，與一般電致或光致發光之P-N界面結構不同，我們發現此P-P有機/無機異質介面也能產生有效率的發光現象。
利用電致發光的方式使電子電洞對於有機/無機異質界面發出有機材料特性波長的光。且此異質界面結合應用於無機氮化鎵發光二極體，調整適當波長的材料混出最適化色溫。經由結果可發現此有機/無機異質界面可發出綠、黃光與無機氮化鎵二極體發出之藍光混成白光，此白光的色座標(0.28,0.30)非常接近標準白光之色座標(0.33,0.33)。藉由此結構改善以往採用螢光粉封裝技術所遇到光損耗、熱效應降低發光效率與壽命等缺失。據此達成本發明之目的與功效，且不使用螢光粉連帶可以降低氮化鎵二極體製造與封裝成本。
而本研究也提出了載子聚集效應來解釋此一P-P有機/無機介面的發光現象，也藉由時間解析的螢光發光(TRPL)與時間解析電致發光光譜(TREL)進行有機/無機異質界面間的載子與激子複合路徑與動力學探討。此研究提出一個新穎的有機/無機異質介面結構發光元件，同時此載子聚集的效應更可廣泛利用於有機/無機異質結構的研究與應用中。
;To further increase the emission spectra for higher color rendering index (CRI) of inorganic light emitting diodes, the hybrid organic/inorganic systems may be a better approach to combine the advantages of both organic and inorganic semiconductors to overcome their respective limitations. This study proposed a novel white light device, which is based on the F8T2/GaN multi quantum wells (MQWs) structure, and identified this device combining the organic and inorganic semiconductors with appropriate charge transport and emission properties under an external forward bias. The International Commission on Illumination (CIE) coordinate of the white-light emission from the present device is at (0.28, 0.30), which is very close to the standard white light (0.33, 0.33). The white-light emission is attributed to the combination of two emission regions of GaN MQWs and the F8T2/p-GaN interface. Here, the carrier localization, which is based on the mobility gap and carrier accumulation, is constructed to explain why the p-p junction of this F8T2/p-GaN interface can contribute to the emission.
The excitation generated excitons and carriers transfer to emission regions while the diffusion and drift flows competitively on short timescales with various relaxation process. With the carrier localization effect, the carrier kinetics and the equilibrium would rearrange before the steady state being achieved. Therefore, the further understanding of carrier dynamics, recombination centers, and losing channels, as well as the proof of the carrier localization can be acquired by using ultrafast techniques of time-resolved photoluminescence (TRPL) and time-resolved electroluminescence (TREL).
In this study, the properties of carrier localization effect and the hybrid white-light device are reported. The p-p junction of F8T2/p-GaN does work and enhance the recombination rate (short lifetime) and emission efficiency of the device. Our work explores the applicability of polymer/GaN epi-layers emitting diodes for electrical and photonic characteristics, providing a new and easy route for producing and modulating the organic/inorganic white light emitting interface. |
