The present study explores the effect of annealing temperature on the charge injection and transport properties of the devices composed of the active layer of poly (3-hexylthiophene) (P3HT):graphene(G) nanocomposites. Changes in the molecular ordering of the P3HT domain induced by the thermal annealing were examined through UV–visible spectroscopy, Raman spectroscopy, and X-ray diffraction studies. The change in the surface morphology upon annealing was observed by field emission scanning electron microscope. Increase in annealing temperature promotes molecular ordering, reduce trap density (from 3.30 × 10¹⁶ cm⁻³for as-cast to 4.06 × 10¹⁵ cm⁻³ after annealing at 200 °C) and trap width (from 0.32 eV to 0.09 eV), resulting in a significant improvement in the mobility (from 4.82 × 10⁻⁷ cm² V⁻¹ s⁻¹ to 1.85 × 10⁻⁴ cm² V⁻¹ s⁻¹). However, junction parameters and diode behavior only enhanced up to annealing temperature of 80 °C. Further increase in annealing temperature leads to a significant increase in the leakage current, and consequently degrades the diode performance. Furthermore, under forward bias, thermionic emission governs the injection mechanism for an as-cast device and the device annealed at 80 °C, while Fowler Nordheim (FN) tunneling controls charge injection at the higher annealing temperature. Under reverse bias, a substantial reduction in tunneling barrier height at high annealing temperature facilitates large hole injection, giving rise to huge leakage current that deteriorates device performance.

本研究探讨了退火温度对由聚（3-己基噻吩）（P3HT）：石墨烯（G）纳米复合材料活性层组成的器件的电荷注入和传输性能的影响。通过紫外可见光谱，拉曼光谱和X射线衍射研究检查了由热退火引起的P3HT域的分子有序变化。通过场发射扫描电子显微镜观察到退火后表面形态的变化。退火温度的升高促进了分子的有序化，降低了陷阱密度（从铸态的3.30×10 ¹⁶  cm ^-3降至4.06×10 ¹⁵  cm ^-3）在200°C退火后）和阱宽度（从0.32 eV到0.09 eV），迁移率显着提高（从4.82×10 ^-7  cm ²  V ^-1  s ^-1到1.85×10 ^-4  cm ²  V ^-1 秒^-1）。但是，结参数和二极管性能仅在退火温度达到80°C时才会增强。退火温度的进一步提高导致漏电流的显着增加，并因此降低了二极管的性能。此外，在正向偏置下，热电子发射控制铸态器件的注入机理，并在80°C的温度下对器件进行退火，而Fowler Nordheim（FN）隧穿控制较高退火温度下的电荷注入。在反向偏置下，高退火温度下隧穿势垒高度的大幅降低有助于大空穴注入，从而产生巨大的泄漏电流，从而降低了器件性能。