光栅局域调控二维光电探测器

近年来,二维材料独特的物理、化学和电子特性受到了越来越多的科研人员的关注.特别是石墨烯、黑磷和过渡金属硫化物等二维材料具有优良的光电性能和输运性质,使其在下一代光电子器件领域具有广阔的应用前景.本文将主要介绍二维材料在光电探测领域上的应用优势,概述光电探测器的基本原理和参数指标,重点探讨光栅效应与传统光电导效应的区别,以及提高光增益和光响应度的原因和特性,进而回顾光栅局域调控在光电探测器中的最新进展及应用,最后总结该类光电探测器面临的问题及对未来方向的展望.     

球状MoS2/WO3复合半导体制备及其对RhB的光催化性能

采用水热法成功制备了MoS₂/WO₃复合半导体光催化剂,分别通过SEM、TEM、EDS、XRD、Raman和DRS对催化剂的形貌,组成及结构进行表征,并用BET模型计算比表面积。对比发现球状MoS₂/WO₃对罗丹明B（RhB）的光降解效率明显高于纯WO₃、片状MoS₂/WO₃复合半导体。针对球状MoS₂/WO₃复合半导体,分别研究了MoS₂不同负载量（0.5%,1%,2%,5%,10%）对RhB光催化降解性能的影响,结果表明MoS₂含量为2%时催化效果最佳。同时,研究了溶液的pH值（pH=1,3,6,7,11）对光催化降解反应活性的影响,结果显示pH=6时降解率最高。当催化剂量增加到1 g·L^-1时,30min后RhB降解率达到96.6%。球状MoS₂/WO₃的瞬态光电流为0.050 6 mA·cm^-2,比纯WO₃提高了2.4倍。经过5次循环实验,球状MoS₂/WO₃复合半导体催化剂仍能保持90%的高降解率。     

退火温度对TiO2/CdSe纳米片异质结薄膜光电性能的影响

采用水热法在FTO上制备（001）高活性晶面主导的TiO₂纳米片薄膜,利用循环伏安法在TiO₂纳米片薄膜上沉积CdSe颗粒,制备了TiO₂/CdSe纳米片异质结薄膜。分别在150、250、350、450 ℃,氩气保护气氛中对样品进行退火。利用X射线衍射仪（XRD）、场发射扫描电镜（FESEM）、X射线光电子能谱分析仪（XPS）、紫外-可见（UV-Vis）分光光度计以及电化学工作站对不同温度退火后的TiO₂/CdSe纳米片异质结薄膜的微观形貌、晶体结构、光电化学性能进行表征和测试。结果表明：六方相CdSe纳米颗粒均匀包覆在TiO₂纳米片表面,直径30 nm左右;随着退火温度的升高CdSe纳米颗粒长大,形成光滑的CdSe薄膜,且晶化程度提高;TiO₂纳米片表面的Se元素与Cd元素发生氧化;TiO₂/CdSe纳米片异质结薄膜对可见光的吸收光谱发生红移,禁带宽度逐渐减小。光电化学性能测试表明随着退火温度的升高,TiO₂/CdSe纳米片异质结薄膜的光电流密度显著提高,开路电压减小,但由于SeO2和CdO的出现,导致填充因子减小,影响光电转换效率的提高。在本实验条件下,TiO₂/CdSe纳米片异质结薄膜的最佳退火温度为150 ℃,填充因子为0.77,光电转换效率达到3.12%。     

Bi2Fe4O9/g-C3N4/UiO-66三元复合材料的协同光催化作用

通过水热法合成具有协同机制的三元复合材料Bi₂Fe₄O₉/g-C₃N₄/UiO-66,研究表明三元复合光催化剂的催化活性要高于二元材料和纯材料。这主要是由于Bi₂Fe₄O₉更易于和g-C₃N₄结合形成稳定的Z-scheme异质结结构,使三元复合材料增强了可见光响应能力,提高了电子-空穴分离能力,增强了空穴和电子的氧化还原能力。     

Solution-processed bilayer photovoltaic devices with nematic liquid crystals

The cross-linking of polymerisable liquid crystalline semiconductors is a promising approach to solution-processable, multilayer, organic photovoltaics. Here we demonstrate an organic bilayer photovoltaic with an insoluble electron-donating layer formed by cross-linking a nematic reactive mesogen. We investigate a range of perylene diimide (PDI) materials, some of which are liquid crystalline, as the overlying electron acceptor layer. We find that carrier mobility of the acceptor materials is enhanced by liquid crystallinity and that mobility limits the performance of photovoltaic devices.     

具有主导晶面的BiOIO3/BiOCl异质结制备与光催化性能

分别以乙二醇/去离子水为溶剂,通过溶剂热/水热法分别制备了具有不同主导晶面的BiOIO₃/{110}BiOCl和BiOIO₃/{001}BiOCl异质结。采用X射线衍射、扫描电子显微镜、能量色散谱和紫外可见漫反射光谱对制备的BiOIO₃/BiOCl光催化剂进行了表征。在可见光照射下,通过对罗丹明 B和苯酚水溶液的光催化降解,考察了 BiOIO₃/BiOCl异质结的光催化活性。结果显示25% BiOIO₃/{110}BiOCl异质结具有最高的光催化效率。BiOIO₃/{110}BiOCl较好的光催化性能是由于其在可见光区较强的光吸收,以及异质结结构和BiOCl所具有的(110)主导晶面有利于光生载流子的分离。超氧自由基(·O₂^-)和空穴(h⁺)是光催化过程中的主要活性物质。此外,根据实验结果探讨了光催化性能增强的机理。     

卤氧化铋复合物光催化剂

利用半导体光催化降解有机污染物与分解水制氢对于解决能源短缺与环境污染这一世界性难题具有重要意义,引起了人们的重视.传统的光催化剂TiO2存在可见光利用率低与光生载流子的复合率高等问题[1-3],因此寻找新型高效光催化剂的工作迫     

The band alignment at CdS/Cu2ZnSnSe4 heterojunction interface

Band alignment at CdS/Cu₂ZnSnSe₄ heterojunction interface is studied by X‐ray photoemission spectroscopy. The Cu₂ZnSnSe₄ thin films are prepared by selenization of electrodeposited Cu‐Zn‐Sn precursors. CdS overlayers with different thickness are sequentially grown on the Cu₂ZnSnSe₄ substrate by pulsed laser deposition process. Photoemission spectra are obtained before and after each growth to study the conduction and valence band offsets at the heterojunction interface. The determined conduction band offset of 0.34 eV indicates a spike‐like ‘type I’ band alignment at CdS/Cu₂ZnSnSe₄ interface. The spike will avoid interface recombination, and it is low enough that electron could transfer from the Cu₂ZnSnSe₄ layer to the buffer layer which is suitable for solar cell's fabrication. Copyright © 2012 John Wiley & Sons, Ltd.     

Band offsets and electronic properties of the Ga2O3/FTO heterojunction via transfer of free-standing Ga2O3 onto FTO/glass

The determination of band offsets is crucial in the optimization of Ga₂O₃-based devices, since the band alignment types could determine the operations of devices due to the restriction of carrier transport across the heterogeneous interfaces. In this work, the band offsets of the Ga₂O₃/FTO heterojunction are studied using x-ray photoelectron spectroscopy (XPS) based on Kraut's method, which suggests a staggered type-Ⅱ alignment with a conduction band offset (ΔE_C) of 1.66 eV and a valence band offset (ΔE_V) of -2.41 eV. Furthermore, the electronic properties of the Ga₂O₃/FTO heterostructure are also measured, both in the dark and under ultraviolet (UV) illuminated conditions (254 nm UV light). Overall, this work can provide meaningful guidance for the design and construction of oxide hetero-structured devices based on wide-bandgap semiconducting Ga₂O₃.     

Magnetic anisotropy manipulation and interfacial coupling in Sm3Fe5O12 films and CoFe/Sm3Fe5O12 heterostructures

The magnetic anisotropy manipulation in the Sm₃Fe₅O₁₂ (SmIG) films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully. By switching the orientation of the Gd₃Ga₅O₁₂ substrates from (111) to (001), the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane. Similar results can also be obtained in the films on Gd₃Sc₂Ga₃O₁₂ substrates, which identifies the universality of such orientation-induced magnetic anisotropy switching. Additionally, the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique. It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films. These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.