熱活化延遲熒光器件中的發(fā)光磁效應(yīng)
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本文關(guān)鍵詞:熱活化延遲熒光器件中的發(fā)光磁效應(yīng) 出處:《中國科學(xué):物理學(xué) 力學(xué) 天文學(xué)》2016年08期 論文類型:期刊論文
更多相關(guān)文章: 熱活化延遲熒光 電致發(fā)光 反向系間竄越 磁效應(yīng)
【摘要】:熱活化延遲熒光(TADF)器件中,三線態(tài)激子可以吸收環(huán)境熱量通過反向系間竄越(RISC)轉(zhuǎn)化為單線態(tài)激子從而發(fā)出延遲熒光,可望實現(xiàn)100%的內(nèi)量子效率.為揭示TADF器件中電致發(fā)光的微觀機制,本文選取4CzTPN-Ph,2CzPN,PIC-TRZ2三種不同帶隙的高效TADF材料制成有機發(fā)光器件,測量并分析器件的電致發(fā)光磁效應(yīng)(MEL).研究發(fā)現(xiàn),盡管這幾種TADF器件具有增強發(fā)光的RISC過程,但它們的MEL曲線卻表現(xiàn)出與不具有RISC過程的普通熒光器件相似的線型,這是由于外加磁場只影響極化子對間的超精細(xì)相互作用,而并不影響激子間的系間竄越與RISC過程.但是,這些TADF器件的磁效應(yīng)幅度卻會隨注入電流的增加而變強,表現(xiàn)出與普通熒光器件相反的結(jié)果,電流對三線態(tài)激子的形成速率kt和單線態(tài)激子的形成速率ks的相對影響(kt/ks)被用來解釋了這一反常結(jié)果.
[Abstract]:In thermally activated delayed fluorescence (TADF) devices, three-wire excitons can absorb environmental heat and convert them into single- line excitons through reverse intersystem channeling, thus emitting delayed fluorescence. The internal quantum efficiency of 100% is expected to be achieved. In order to reveal the micromechanism of electroluminescence in TADF devices, 4 CzTPN-Phan 2CzPN is selected in this paper. Three kinds of high efficiency TADF materials with different band gaps were fabricated by PIC-TRZ2. The electroluminescent magnetic effects of the devices were measured and analyzed. Although these TADF devices have enhanced luminescence RISC process, their MEL curves show a linear pattern similar to that of conventional fluorescent devices without RISC process. This is because the applied magnetic field only affects the hyperfine interaction between polaron pairs and does not affect the intersystem transition between excitons and the RISC process. However, the amplitude of magnetic effect of these TADF devices will increase with the increase of the injection current, which is contrary to the results of conventional fluorescent devices. The relative effect of current on the formation rate of three-wire excitons (kt) and singlet state excitons (k _ s) is used to explain this anomalous result.
【作者單位】: 西南大學(xué)物理科學(xué)與技術(shù)學(xué)院;
【基金】:國家自然科學(xué)基金(編號:11374242) 中央高校基本科研業(yè)務(wù)費專項資金(編號:XDJK2015C149)資助項目
【分類號】:TN383.1
【正文快照】: 有機發(fā)光二極管(OLED)因其具有制備簡單、價格低廉、柔性和超薄等優(yōu)勢,正逐步走進人們的日常生活[1,2].普通熒光OLED只有25%的電子-空穴對能復(fù)合成單線態(tài)激子退激發(fā)光,剩下75%的三線態(tài)激子只能以非輻射退激的形式把能量耗散掉,其內(nèi)量子效率(IQE)被限制在25%以內(nèi)[3].磷光OLED依
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