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Bright, stable, and efficient red light-emitting electrochemical cells using contorted nanographenes.
Nanoscale Horizons ( IF 8.0 ) Pub Date : 2019-12-20 , DOI: 10.1039/c9nh00641a
Elisa Fresta 1 , Kevin Baumgärtner , Juan Cabanillas-Gonzalez , Michael Mastalerz , Rubén D Costa
Affiliation  

This work rationalizes, for the first time, the electroluminescent behavior of a representative red-emitting contorted nanographene -i.e., hexabenzoovalene derivative - in small molecule light-emitting electrochemical cells (SM-LECs). This new emitter provides devices with irradiances of ca. 220 μW cm-2 (242 cd m-2), external quantum efficiencies (EQE) of 0.78% (<25% loss of the maximum theoretical EQE), and stabilities over 200 h. Upon optimizing the device architecture, the stability increased up to 3600 h (measured) and 13 000 h (extrapolated) at a high brightness of ca. 30 μW cm-2 (34 cd m-2). This represents a record stability at a high brightness level compared to the state-of-the-art SM-LECs (1000 h at 0.3 μW cm-2). In addition, we rationalized one of the very rare LEC examples in which the changes of the electroluminescence band shape relates to the dependence of the relative intensity of the vibrational peaks with electric field, as corroborated by dynamic electrochemical impedance spectroscopy assays. Nevertheless, this exclusive electroluminescence behavior does not affect the device color, realizing one of the most stable, bright, and efficient red-emitting SM-LECs up to date.

中文翻译:

使用扭曲的纳米石墨烯的明亮,稳定,高效的红色发光电化学电池。

这项工作首次使小分子发光电化学电池(SM-LEC)中具有代表性的红色发光扭曲纳米石墨烯(即六苯并戊烯衍生物)的电致发光行为合理化。这种新的发射器可为设备提供约270的辐照度。220μWcm-2(242 cd m-2),外部量子效率(EQE)为0.78%(最大理论EQE损失<25%),稳定性超过200小时。在优化器件架构后,在高亮度ca时,稳定性增加到3600 h(实测)和13 000 h(外推)。30μWcm-2(34 cd m-2)。与最新的SM-LEC(在0.3μWcm-2下1000小时)相比,这代表了在高亮度水平下的记录稳定性。此外,我们合理化了一个非常罕见的LEC实例,其中电致发光谱带形状的变化与振动峰的相对强度与电场的相关性有关,这通过动态电化学阻抗谱测定法得到了证实。然而,这种独特的电致发光性能不会影响器件的颜色,从而实现了迄今为止最稳定,明亮和最有效的发红光SM-LEC之一。
更新日期:2020-03-02
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