以微共振腔效應推估有機發光電化學元件複合區位置

Abstract

探測三明治結構有機發光電化學元件(light-emitting electrochemical cells, LEC) 隨時間不同而改變的複合區位置之技術，對於改善元件效率或光色是非常重要的。因為此技術可提供直接的實驗證據來證實當調整元件參數時，載子平衡也被改變了。然而，以直接成像的方式來觀察發光層薄膜裡的複合區變化情形是非常困難的。在本論文中，將提出一種替代方式來得知複合區位置變化，利用微共振腔效應以動態探測方式來推估複合區位置移動情形，具微共振腔結構的三明治結構的有機發光電化學元件其波長會受光輸出耦合效率影響，因此當複合區移動時，電激發光頻譜也會跟著改變，因此，藉由調整以模擬方式輸出的電激發光頻譜與量測出的電激發光頻譜作匹配對照，可推估出複合區移動大概位置，有了此推估方法，可由量測及模擬出的結果得知載子平衡會明顯受載子傳輸、載子注入的調整而影響改變，更顯示微共振腔效應對於探討三明治結構的有機發光電化學元件之複合區位置變化有很大影響。

Techniques of probing for time-dependent evolution of recombination zone position in sandwiched light-emitting electrochemical cells (LEC) would be highly desired since they can provide direct experimental evidence to confirm altered carrier balance when device parameters are adjusted. However, direct imaging of recombination zone in a thin emissive layer could not be obtained easily. In this work, we propose an alternative way to extract evolution of recombination zone position by utilizing microcavity effect. Recombination zone positions can be estimated by fitting the measured electroluminescence spectra to simulated output spectra based on microcavity effect and properly adjusted emissive zone positions. With this tool, effects of modified carrier transport and carrier injection on performance of LEC are studied and significantly altered carrier balance can be measured, revealing that microcavity effect is effective in tracing evolution of recombination zone position in sandwiched LEC.