We have investigated the failure mechanism of organic functional materials and organic light-emitting diodes (OLEDs) by annealing at high temperatures. We found that N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) doped molybdenum oxide and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene doped cesium carbonate can enhance the thermal stability significantly. The former composite film reveals the ions of NPB, as observed by X-ray photoelectron spectroscopy (XPS), the formation of which shows that NPB receives the electron that Mo loses. Meanwhile, it is stable for the binding energy of the element in the latter composite film from the XPS image. Through the research of carrier-only cells, the observation indicates that the thermal stability of the doped cell is better than that of the undoped cell at high temperatures. The current efficiency of the doped device is only reduced by 12% after annealing at 80℃; meanwhile the lifetime reaching 208 h is the longest among that of the devices. Simultaneously, the undoped device represents a larger decline even of about 30% with the lifetime reaching just 40 h. We assumed that the enhanced heat-resisting properties of organic materials by inorganic doping might be attributed to the decrease of energy barrier and the reduction of the interface charge accumulation phenomenon caused by high temperature. Inorganic doping paves an alternative way to substitute for synthesizing expensive functional materials with high glass transition temperature.

中文翻译：

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通过热掺杂金属氧化物制成坚固的有机功能材料

我们通过高温退火研究了有机功能材料和有机发光二极管 (OLED) 的失效机制。我们发现 N,N'-双(萘-1-基)-N,N'-双(苯基)-联苯胺 (NPB) 掺杂的氧化钼和 1,3,5-三[(3-吡啶基)-苯-3-基]苯掺杂碳酸铯可以显着提高热稳定性。X射线光电子能谱（XPS）观察到，前者的复合膜显示出NPB的离子，其形成表明NPB接受了Mo失去的电子。同时，从XPS图像来看，后者复合膜中元素的结合能是稳定的。通过对纯载流子电池的研究，观察表明掺杂电池在高温下的热稳定性优于未掺杂电池。掺杂器件在80℃退火后电流效率仅降低12%；同时达到208 h的寿命是所有器件中最长的。同时，未掺杂的器件甚至下降了约 30%，寿命仅达到 40 小时。我们假设通过无机掺杂增强有机材料的耐热性能可能归因于能量势垒的降低和高温引起的界面电荷积累现象的减少。无机掺杂为替代合成具有高玻璃化转变温度的昂贵功能材料铺平了道路。未掺杂的器件下降幅度更大，甚至约 30%，寿命仅达到 40 小时。我们假设通过无机掺杂增强有机材料的耐热性能可能归因于能量势垒的降低和高温引起的界面电荷积累现象的减少。无机掺杂为替代合成具有高玻璃化转变温度的昂贵功能材料铺平了道路。未掺杂的器件下降幅度更大，甚至约 30%，寿命仅达到 40 小时。我们假设通过无机掺杂增强有机材料的耐热性能可能归因于能量势垒的降低和高温引起的界面电荷积累现象的减少。无机掺杂为替代合成具有高玻璃化转变温度的昂贵功能材料铺平了道路。