針對兩種相同元件結構但是不同敏化層組成的有機藍光二極體，利用磁場效應的角度研究主動層三重態-三重態湮滅上轉換(triplet-triplet annihilation upconversion (TTAUC))延遲螢光機制的運作情形。元件的敏化層和放光層皆有參與放光，透過定量fitting的方式驗證多光源系統下磁電致發光效應(magneto-electroluminescence (MEL))是emission-dependent的。室溫下磁電致發光效應的研究發現在敏化層中摻入少量Ir(ppy)3的元件能表徵到明顯提升的TTAUC efficiency，不僅驗證了文獻中提出的機制模型也表明少量Ir(ppy)3的摻入有助於利用大量long-lived triplet excitons和提升 energy transfer rate。另外變溫的磁電致發光效應研究發現到兩種元件的TTAUC在低溫下都沒有被增強，未摻雜的元件在低溫下因為Alq3的TTA effect增強，不利於放光層TTAUC的提升；而摻雜的元件在低溫下觀察到整體主動層的TTA強度有逐漸被弱化的趨勢，最後利用變溫磁電導效應(magnetoconductance (MC))表徵到隨溫度下降而漸增的triplet exciton charge reaction (即TPQ)，成功解釋了低溫下被抑制的TTA effect。

We investigate the photophysics in two blue organic light-emitting diodes through magnetic field effects (MFEs). The only difference between them is whether the sensitizer in the active layer is doped or not. Because both the sensitizer and the emitter contribute to the emission, we should individually extract each light source and then conduct subsequent mechanisms analysis. We successfully verify that doping a small amount of Tris[2-phenylpyridinato-C2,N] Iridium(III) (Ir(ppy)3) into the sensitizer is a critical method to both largely quench the green emission and enhance triplet-triplet annihilation (TTA) efficiency in the emitter simultaneously. Under the low-temperature conditions, we are unable to observe enhanced TTA in either device. In the case of the undoped device, there are no signs of unbalanced carrier behavior during the cooling process. However, an enhanced TTA feature is observed in the sensitizer, resulting in a reduction of triplet excitons available for TTA upconversion in the emitter. In the case of the doped device, we attribute the suppressed TTA phenomena, with the decreasing temperature, to the gradually stronger triplet exciton charge reaction.

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