| dc.description.abstract | Organic photodetectors hold immense potential for convert light energy into electrical energy applications. However, most organic photodetectors use bulk heterojunction structures as their photoactive layers to increase exciton dissociation efficiency, but this can result in a high dark current, consequently impacting the device′s performance. To address this issue, this study introduces the concept of charge-blocking layers to enhance the performance of organic photodetectors, aiming to achieve low dark current and high photocurrent in the device design. The experiments employed Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the active layer materials and analyzed the results using five different blocking layers.
Firstly, the addition of the insulating material hafnium oxide (HfO2) confirmed the expected reduction in the dark current due to charge blocking effect, but the photocurrent was not increased. Subsequently, the zinc oxide (ZnO) blocking layer prepared by the precursor was investigated, revealing that different ZnO thicknesses would result in significant variations in device performances. Additionally, the commercially available ZnO inks with work functions of 4.3 eV and 3.9 eV were used as the blocking layers. It was found that the higher work function ZnO effectively suppressed the dark current of the photodetector. In contrast, adding lower work function ZnO led to a substantial increase in both dark and photocurrents. The differences observed in the devices with different work functions also indicate that the work function of ZnO affects the performance of the device.. Finally, by blending two types of ZnO inks with different work functions at an appropriate ratio, the organic photodetector can successfully achieve the reduced dark current and increased photocurrent, resulting in an overall performance improvement. At a -1V bias voltage, the optimal device demonstrated a responsivity of 0.62 A/W, detectivity of 1.84×10^12 Jones, and EQE of 146.9 %. The rise time of 16.5 µs and fall time of 106.5 µs. | en_US |