Luo Guangcan, Zhang Ziling, Jiang Jing, Liu Yang, Li Wei, Zhang Jingquan, Hao Xia, Wang Wenwu
College of Materials Science and Engineering, Sichuan University Chengdu 610064 China
Institute of New Energy and Low-carbon Technology, Sichuan University Chengdu 610027 China.
RSC Adv. 2021 Feb 17;11(13):7682-7692. doi: 10.1039/d0ra10420e. eCollection 2021 Feb 10.
Facile, convenient and low-cost processes, including a chemical hydrothermal method and impregnation technique, were demonstrated to fabricate a self-powered ZnO nanorod array/CuSCN/reduced graphene oxide (rGO) ultraviolet photodetector. ZnO nanorods (NRs) were fully filled and encased by the CuSCN layer, in which CuSCN acts as the primary hole-transport layer and an electron reflection layer, blocking the electron transfer towards the Au electrode and reducing the electron-hole pair recombination. After annealing, this encapsulated structure further reduces the surface state defects of ZnO NRs, which can isolate the electron exchange with oxygen in the air, dramatically reducing the rise and fall time; it also forms a p-n junction, providing a built-in electric field to improve the photoresponse without applying external power. The rGO layer was coated on the surface of CuSCN as the secondary hole-transport layer and then annealed, which could effectively block Au from entering CuSCN and contacting ZnO along cracks and holes during vapor deposition, avoiding the formation of leakage channels. Furthermore, due to the ultra-high carrier mobility and the increase in work function after Au doping, the functionalized graphene could reduce the valence band shift, which is beneficial to enhance hole transport. Meanwhile, rGO obstructs the undesired barrier formed by electrical potential-induced reaction of Au with thiocyanate anions. Finally, the ZnO NR/CuSCN/rGO ultraviolet photodetector exhibits a significant enhancement in device performance (responsivity: 18.65 mA W at 375 nm under 65 mW cm illumination, rectification ratio: 5690 at ±1 V), which is better that of than ZnO NR/CuSCN structure (10.88 mA W, 10.22 at ±1 V) and maintains the 100 ms response time.
通过包括化学水热法和浸渍技术在内的简便、便捷且低成本的工艺，成功制备了一种自供电的氧化锌纳米棒阵列/硫氰化亚铜/还原氧化石墨烯（rGO）紫外光电探测器。氧化锌纳米棒（NRs）被硫氰化亚铜层完全填充并包裹，其中硫氰化亚铜充当主要的空穴传输层和电子反射层，阻止电子向金电极转移并减少电子-空穴对的复合。退火后，这种封装结构进一步减少了氧化锌纳米棒的表面态缺陷，能够隔离与空气中氧气的电子交换，显著缩短上升和下降时间；它还形成了一个p-n结，提供一个内建电场以在不施加外部电源的情况下改善光响应。rGO层作为次要的空穴传输层涂覆在硫氰化亚铜表面，然后进行退火处理，这可以有效阻止金在气相沉积过程中沿着裂纹和孔洞进入硫氰化亚铜并与氧化锌接触，避免形成泄漏通道。此外，由于超高的载流子迁移率以及金掺杂后功函数的增加，功能化的石墨烯可以减少价带偏移，这有利于增强空穴传输。同时，rGO阻碍了由金与硫氰酸根阴离子的电势诱导反应形成的不期望的势垒。最终，氧化锌NR/硫氰化亚铜/rGO紫外光电探测器在器件性能方面表现出显著增强（响应度：在65 mW/cm²光照下，375 nm处为18.65 mA/W，整流比：±1 V时为5690），优于氧化锌NR/硫氰化亚铜结构（10.88 mA/W，±1 V时为10.22），并保持100 ms的响应时间。
