B Hanna, K P Surendran, K N Narayanan Unni
Academy of Scientific and Innovative Research (AcSIR), CSIR-NIIST Campus Thiruvananthapuram 695019 India
Photosciences and Photonics Section, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology Thiruvananthapuram-695019 Kerala India.
RSC Adv. 2018 Nov 6;8(65):37365-37374. doi: 10.1039/c8ra07312k. eCollection 2018 Nov 1.
Ultraviolet (UV) photodetectors have drawn extensive attention due to their numerous applications in both civilian and military areas including flame detection, UV sterilization, aerospace UV monitoring, missile early warning, and ultraviolet imaging. Zinc oxide (ZnO)-based UV detectors exhibit remarkable performance; however, many of them are not visible-blind, and the fabrication techniques involve a high-temperature annealing step. Here, we fabricated a p-n junction photodiode based on annealing-free ZnO thin films prepared from ZnO nanoparticles and ,'-di(1-naphthyl)-,'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). NPB was chosen due to its transparent nature in the visible region and high hole mobility. The ZnO nanoparticles and thin films were characterized by UV-visible absorption spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), dynamic light scattering (DLS) particle size analysis, Fourier-transform infrared (FTIR) spectroscopy, photoluminescence spectroscopy, XRD and profilometry. The device exhibited responsivity of 0.037 A/W and an external quantum efficiency (EQE) of 12.86% at 5 V bias under 360 nm illumination. In addition, with no biasing, the device exhibited an on-off ratio of more than 10 and a linear dynamic range (LDR) of 63 dB. A high built-in potential at the ZnO/NPB interface could be the reason for this performance at zero bias. The rise and fall times were 156 ms and 319 ms, respectively. The results suggest that a visible-blind UV photodetector with acceptable performance can be fabricated using annealing-free ZnO films, which may lead to the realization of flexible detectors due to the low-temperature processes involved.
紫外（UV）光电探测器因其在民用和军事领域的众多应用而备受关注，这些应用包括火焰探测、紫外线杀菌、航空航天紫外线监测、导弹预警以及紫外线成像。基于氧化锌（ZnO）的紫外探测器表现出卓越的性能；然而，其中许多并非可见光盲探测器，且制造技术涉及高温退火步骤。在此，我们基于由氧化锌纳米颗粒和α,α'-二（1-萘基）-α,α'-二苯基-（1,1'-联苯）-4,4'-二胺（NPB）制备的无退火氧化锌薄膜制造了一个p-n结光电二极管。选择NPB是因其在可见光区域的透明特性和高空穴迁移率。通过紫外-可见吸收光谱、原子力显微镜（AFM）、扫描电子显微镜（SEM）、动态光散射（DLS）粒度分析、傅里叶变换红外（FTIR）光谱、光致发光光谱、XRD和轮廓仪对氧化锌纳米颗粒和薄膜进行了表征。该器件在360 nm光照下、5 V偏压下表现出0.037 A/W的响应度和12.86%的外量子效率（EQE）。此外，在无偏压情况下，该器件的开/关比大于10，线性动态范围（LDR）为63 dB。氧化锌/ NPB界面处的高内建电势可能是该器件在零偏压下具有此性能的原因。上升时间和下降时间分别为156 ms和319 ms。结果表明，使用无退火氧化锌薄膜可以制造出性能可接受的可见光盲紫外光电探测器，由于所涉及的低温工艺，这可能会促成柔性探测器的实现。
