Here, we report the hole injection role of p-type conjugated polymer layer in phosphorescent organic light-emitting devices (OLEDs). Poly(3-hexylthiophene) (P3HT) nanolayers (thickness = ~1 nm thick), which were subjected to thermal annealing at 140 °C by varying annealing time, were inserted between indium tin oxide (ITO) anodes and hole transport layers (N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine, NPB). The 1 nm-thick P3HT layers showed very weak absorption in the visible light range of 500~650 nm. The device results disclosed that the presence of P3HT layers were just able to improve the charge injection of OLEDs leading to an enhanced luminance irrespective of thermal annealing condition. The highest luminance and efficiency were achieved for the OLEDs with the P3HT layers annealed at 140 °C for 10 min. Further annealing for 30 min resulted in turn-down of device performances. The emission color was almost unchanged by the presence of P3HT layers even though the color coordinates were marginally fluctuated according to the annealing time. The present result delivers the possibility to use p-type conjugated polymers (i.e., P3HT) as a hole injection layer in OLEDs.

中文翻译：

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p 型共轭聚合物纳米层在磷光有​​机发光器件中的空穴注入作用

在这里，我们报告了 p 型共轭聚合物层在磷光有​​机发光器件 (OLED) 中的空穴注入作用。聚（3-己基噻吩）（P3HT）纳米层（厚度 = ~1 nm 厚），通过不同的退火时间在 140 °C 下进行热退火，插入氧化铟锡（ITO）阳极和空穴传输层（N ,N'-双(萘-1-基)-N,N'-双(苯基)-联苯胺，NPB)。1 nm 厚的 P3HT 层在 500~650 nm 的可见光范围内表现出非常弱的吸收。器件结果表明，无论热退火条件如何，P3HT 层的存在都能够改善 OLED 的电荷注入，从而提高亮度。P3HT 层在 140°C 下退火 10 分钟的 OLED 实现了最高的亮度和效率。进一步退火 30 分钟导致器件性能下降。尽管颜色坐标根据退火时间略有波动，但由于 P3HT 层的存在，发光颜色几乎没有变化。目前的结果提供了使用 p 型共轭聚合物（即 P3HT）作为 OLED 中的空穴注入层的可能性。