碳点修饰石墨毡电极在ZnI_2溶液中的电化学性能

通过溶剂热法在石墨毡(GF)上制备碳点(CD),将其作为电极,在碘化锌(ZnI_2)电解液中测量其电化学性能,研究其作为ZnI_2储能器件的电极对储能器件性能的影响。主要通过不同制备时间的溶剂热法制备碳点,研究不同的制备时间对碳点制备的影响。对碳点修饰的石墨毡进行快速热退火,研究退火对石墨毡电极性能的影响。通过场发射扫描电子显微镜(FE-SEM)、X射线衍射仪(XRD)和喇曼光谱对电极表面进行了表征。通过循环伏安曲线(CV)、电化学阻抗谱(EIS)和计时电位法研究其电化学性能。研究结果表明,通过9 h、180℃下溶剂热法制备的CD修饰GF具有最好的电化学性能。     

纳米银线/还原石墨烯复合材料的制备与表征

用改进的Hummer法制备了氧化石墨烯(GD),并制备 了表面用聚乙烯吡咯烷酮修饰的纳米银线(AgNWs), 通过原位还原法将二者复合成一种新型的水溶性AgNWs/还原石墨烯(RGD)材料,克服了石 墨烯材料不易分散 的缺点。用X射线衍射(XRD)、紫外-可见分光(UV-vis)光度计、扫描电子显 微镜(SEM)和傅里 叶变换红外(FT-IR)光谱分析仪对样品结构和形貌进行了表征。结果表明,制备的AgNWs/RG D材料具有与前驱 体不同的物理参数,有望在非线性光学、光电传感器和生物抑菌等方面有良 好的表现。     

GO/PANI改性环氧树脂@TiO2/CdS涂层的光生阴极保护性能

为解决二氧化钛/硫化镉(TiO₂/CdS)复合材料作为光生阴极防腐保护材料无法对金属提供持久性光生阴极保护、导电率低和载流子复合率高等问题,引入氧化石墨烯(GO)和聚苯胺(PANI)材料,通过水热法和原位聚合法制备了TiO₂/CdS/GO/PANI复合材料,将其作为改性环氧树脂涂层,制备出兼具优异光电转换性能和防腐性能的双功能环氧树脂基涂层。通过对Q235碳钢(Q235 CS)表面进行涂覆,研究了复合涂层的光生阴极保护电化学性能和防腐性能参数。结果表明,TiO₂/CdS/GO/PANI修饰后的环氧树脂基涂层表现出优异的光电化学性能和防腐性能,光电流密度达到0.15 A/cm²,开路电位为-0.8 V,防腐蚀效率高达98.55%。     

NrGO-RuO_(2)复合正极对有机电解液锂空气电池性能影响研究北大核心CSCD

动力电池作为新能源汽车最重要的部分之一,它的容量直接决定了新能源汽车续航里程的长短。随着新能源汽车的普及,具有高能量密度的锂空气电池成为了目前的研究热点之一。而高性能的空气正极对提升锂空气电池电化学性能至关重要。采用水热法制备氮掺杂石墨烯/二氧化钌(NrGO-RuO_(2))复合正极,通过X射线衍射、X射线光电子能谱、扫描电子显微镜和氮气(N_(2))等温吸-脱附等测试对其晶体结构、元素组成、表面形貌和孔隙结构进行分析,并通过恒流定容充放电、深度放电、电化学交流阻抗图谱等测试分析其对锂空气电池性能的影响。研究表明:与rGO和rGO-RuO_(2)复合正极相比较,NrGO-RuO_(2)复合正极具有较高的循环、深度放电性能和较低的电荷转移阻抗。装配NrGO-RuO_(2)复合正极的锂空气电池,循环次数达到90次,放电深度达到4309 mAh/g,电荷转移阻抗为39.27Ω·cm^(2)。     

PZT基复合材料的3D打印制备及其柔性传感性能研究

为提高柔性可穿戴传感器的电信号输出能力,设计并制备了以聚二甲基硅氧烷(PDMS)为基体,锆钛酸铅(PZT)为压电相的0-3型压电复合材料。并探究了不同固相含量对浆料流变性能的影响。结果表明,浆料的粘度与剪切模量随银修饰PZT质量分数(w(PZT))的增加而增加,w(PZT)=38%时浆料屈服点为398.1 Pa,具有最优的可打印性。在电信号测试中,经银修饰样品最大电压峰-峰可达20.54 V,约为未经银修饰样品最大电压峰-峰值的5倍。弯曲测试中,在长度之差ΔL=7 cm时,样品电压峰-峰值为55 mV,证明样品具备柔性传感性能。     

Mn^(2+)掺杂CdS量子点敏化太阳电池的性能北大核心

采用连续式离子层吸附与反应(SILAR)法不仅成功制备出CdS量子点敏化的TiO2纳米晶光阳极,而且实现了Mn2+在CdS量子点晶格内部的可控掺杂。应用场发射扫描电子显微镜(FESEM)对电极的形貌进行了分析和表征。继而通过组装光伏电池研究Mn2+掺杂浓度与电池性能之间的关系。通过测量其紫外-可见吸收光谱及电流密度-电压(J-V)特性曲线考察电池性能随Mn2+掺杂量的变化规律。在研究中发现,掺杂适量的Mn2+有助于提高CdS/TiO2光阳极对可见光的吸收,进而增强太阳电池的能量转换效率。当Mn2+浓度为0.075 mmol/L时,量子点敏化太阳电池(QDSSC)的能量转换效率可达2.85%,较未掺杂的光阳极试样性能提高约50%。     

TiO2基染料敏化太阳能电池的表面修饰及性能研究

采用水热法制备TiO₂浆料,用La(NO₃)₃溶 液浸泡TiO₂薄膜获得修饰电极。用X射线光电子能谱(XPS) 和扫描电子显微镜(SEM)对修饰电极的主要成分及形貌进行表征的结果显示,电极薄膜分为 上下两层,表 面包覆层粒径较大,为La₂O₃颗粒;下层颗粒粒径较小,为TiO₂颗粒。电流-电压测 试结果显示,与修饰 前相比,用La(NO₃)₃溶液浸泡30min获得的膜电极性能最优,使 开路电压和短路电流分别提高了6.8%和 18.5%。电化学阻抗谱(EIS)测试结果表明,相同偏压下,TiO₂/La ₂O₃电极界面复合电阻比TiO₂要大,说明 La₂O₃包覆层在一定程度上抑制了界面的电子复合,改善了电池的光电化学性能。     

CaBi2Ta2O9:Pr3+黄色荧光粉的制备与性能研究

采用高温固相反应法,制备了系列Pr3+掺杂的CaBi2Ta2O9(CBTO:Pr3+)Bi层状结构铁电氧化物(BLSFs)粉体。利用X射线衍射(XRD)、扫描电子显微镜(SEM)对样品的晶体结构和形貌进行了表征。利用积分球式分光光度计和荧光光谱仪对样品的光学性能进行了分析。XRD结果表明,所生成的样品均为CBTO纯相。样品的吸收和激发光谱表明,在449~500nm波长范围存在Pr3+的f-f跃迁吸收;样品的发射光谱由绿光(525~575nm)和红光(575~700nm)发射两部分组成,避免了白光LED中再吸收的问题。随着Pr3+掺杂浓度的增加,样品的发光强度先增强后减弱,当Pr3+的掺杂浓度为2mol%时发光强度最大。研究了Ca0.98Pr0.02Bi2Ta2O9的热稳定性,并通过计算得到其热猝灭激活能E=0.24eV。显色指数(CIE)色坐标图表明,所制备的样品可以被蓝光有效激发而发出黄光。研究结果表明,CBTO:Pr3+可以用于蓝光LED芯片激发用的黄色荧光粉。     

氧分压对磁控溅射制备IGZO薄膜光电特性的影响

通过磁控溅射技术在玻璃基板上制备氧化铟镓锌(IGZO)薄膜,为了研究不同氧分压对IGZO薄膜结构及光电特性的影响,在不同的氧分压0,0.015,0.06和0.24 Pa下制备了不同样品。样品的沉积速率、成分结构、面电阻及光电性质分别用椭偏仪、X射线光电子能谱(XPS)和四点探针等方法进行了测量。实验结果表明,随着氧分压的增大,IGZO薄膜的沉积速率呈下降趋势,不同氧分压的IGZO薄膜的元素比例(In∶Ga∶Zn)差异不大,在可见光的范围内其氧分压为0 Pa以上时,IGZO薄膜平均透过率均超过80%,阻值随氧分压的增加而增大。制作了不同氧分压以IGZO为沟道层的薄膜晶体管,其迁移率为5.93~9.42 cm2·V-1·s-1,阈值电压为3.8~9.2 V。     

Li_2O-Nb_2O_5-TiO_2微波介电陶瓷掺杂改性研究

采用传统的固相反应法制备Li-Al-B(LAB)掺杂立方晶系Li2O-Nb2O5-TiO2(LNT)微波介电陶瓷。运用XRD、SEM和微波介电性能测试等手段,研究了LAB掺杂对样品烧结性能及微波介电性能的影响。结果表明,在LNT陶瓷中添加LAB,有效促进LNT陶瓷烧结,使材料的介电常数和品质因数显著提高。当掺入LAB的质量分数为4%时,样品在900℃保温2h后烧结致密,并获得最佳微波性能:介电常数εr=18.05,品质因数与频率的乘积Q×f=22 040GHz(f=6.41GHz),频率温度系数τf=-20.74×10-6/℃。     

Employing 4-methoxybenzoic acid interfacial-modification to enhance the photovoltaic performance of CdS quantum dot-sensitized solar cells

The effect of incorporating self-assembled monolayers of 4-methoxybenzoic acid (MBA) on CdS quantum dot-sensitized (QDSSC) solar cells based on ZnO nanorods was evaluated. The MBA was deposited on the ZnO photoanode, with the deposition time being a process variable. Photoluminescence spectra indicated that the MBA modification can suppress the photogenerated electron–hole recombination processes and presumably passivate the surface defects. The ultraviolet photoemission spectroscopy results prove that MBA forms an energy barrier at the interface of ZnO and CdS which may retard the back transfer of electrons. Overall the inclusion of MBA imparts a weak positive enhancement of the photovoltaic performance of these QDSSCs and this is an approach that may be developed to give stronger effects using alternative chemistries.     

染料敏化TiO_2单晶纳米棒阵列太阳电池的性能

采用水热法一步合成出TiO2单晶纳米棒有序阵列,进而制备出染料敏化太阳电池。重点探讨了退火时间变化对电池光电转化效率的影响。研究结果表明,与未退火的纳米棒组装而成的电池相比,退火后的纳米棒电池显示出更高的光电转化效率。并且当退火时间为7 min时,光电转化效率最高(5.05%),提高到未退火电池光电转化效率的300%以上。电池性能提高的原因有:TiO2纳米棒阵列与衬底间结合力的增强有利于电子传输;表面态缺陷的减少有利于抑制光生载流子的复合。结合SEM,TEM和J-V曲线等表征手段探讨了这一现象背后的物理机制。     

Enhanced electron injection/transportation by surface states increment in mesoporous TiO2 dye-sensitized solar cells

A strategy of surface modification to the mesoporous TiO2 photoanode with hydrochloric acid treatment was used in this study, and it was found that short circuit current and photovoltaic efficiency of dyesensitized solar cells (DSSCs) were increased by 5.5% and 8.9% respectively. The improvement was attributed to the reduced impedances in the TiO2 film and at the TiO2/dye/electrolyte interface. It was showed that the increased surface electronic states could remarkably prolong electron lifetime, which was responsible for the reduction of impedances. Under these quasi-continuous states in mesoporous structure, the electron injection/transportation can be notably facilitated, which will be beneficial for the DSSC performance.     

Quantum dot photoelectrochemical solar cells based on TiO2-SrTiO3 heterostructure nanotube array scaffolds

Titania-Strontium titanate (TiO2-SrTiO3)nanotube array with heterostructure has been demonstrated as an efficient scaffold applied to quantum dot photoelectrochemical solar cells. Quantum dot CdS serviced as solar light absorbent is chosen as an example to illustrate superior performance and deposited on scaffolds by successive ionic layer adsorption and reaction (SILAR) technique. The photoelectrochemical performance of such solar cell is strongly dependent on the structure of heterostructured scaffolds. Only well-dispersed SrTiO3 nanocrystallites on TiO2 could improve the overall conversion efficiency. Transient absorption spectra and photoelectrochemical measurements show that the formation of SrTiO3 energy gradient between TiO2 and electrolyte slows down the rate of electronic injection from 19.3 × 108 to 6.30 × 108 s 1, while it greatly increases electronic collection efficiency via reduced charge recombination. Cadmium sulfide (CdS) quantum dots used to decorate TiO2-SrTiO3 (1 h hydrothermal treatment) electrode exhibits superior photoelectrochemical performance with nearly 70% increase in external quantum efficiency at 460 nm and also in overall cell conversion efficiency. The photostability and high efficiency properties of TiO2SrTiO3 composites would enable its practical application in solar energy conversion devices.     

低温制备柔性染料敏化太阳电池TiO2薄膜电极

采用丝网印刷技术在柔性基底ITO/PET上制备TiO2多孔薄膜,经过低温烧结得到TiO2多孔薄膜电极。以D102染料为敏化剂,KI/I2为电解质,Pt电极为对电极,制成电池后测试了电池的光电性能。结果表明:以乙醇作为分散剂添加到P25粉体中,采用丝网印刷技术制膜,100℃低温烧结可以在柔性基底ITO/PET上制备出表面粗糙度良好、具有一定光电性能的TiO2多孔薄膜电极,用其制作的太阳电池转换效率达1.33%。     

聚乙二醇共水热合成TiO2纳米晶多孔薄膜

以钛酸丁酯为原料,在水热过程中加入聚乙二醇(分子量2 000)合成TiO2纳米晶,并制备多孔薄膜用于染料敏化太阳能电池(DSSCs)。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、台阶仪、紫外-可见分光光度计(UV-vis)对纳米晶粒的晶体结构、薄膜的表面形貌、厚度和光学吸收性能以及电池的光电能量转换性能随聚乙二醇的加入量变化的规律进行了探索。结果表明,聚乙二醇的加入抑制了锐钛矿相TiO2晶粒的生长,诱导了金红石相的形成。当聚乙二醇的加入量为TiO2质量的5%时性能达到最佳,采用单层多孔薄膜以及不添加四-叔丁基吡啶的电解质组装的电池获得了2.86%的光电能量转换效率。     

TiO_2纳米管阵列对染料敏化太阳能电池性能的影响

通过恒压阳极氧化法在Ti箔表面制备了结构规整的TiO2纳米管阵列,研究了氧化时间和退火温度对纳米管阵列的尺寸和晶体结构的影响。用制得的纳米管阵列电极组装了染料敏化太阳能电池(DSSC),研究了纳米管长度、退火温度和电极面积对DSSC光电性能的影响。结果表明,纳米管管径和壁厚均与氧化时间无关,而纳米管长度则随着氧化时间延长而增加。在450℃及更低温度退火时,纳米管中只出现锐钛矿相;而在500℃退火时,纳米管中则又出现了金红石相。由厚度为27μm、退火温度为450℃的纳米管阵列电极组装成的DSCC具有最佳的光电转化性能。DSCC的光电转化效率随电极面积的增加而降低。     

Enhanced performance of hybrid solar cells based on ordered electrospun ZnO nanofibers modified with CdS on the surface

To improve the performance of the hybrid solar cells based on electrospun zinc oxide nanofibers/poly(3-hexylthiophene) (ZnO/P3HT), we modified the ZnO nanofibers with nanocrystalline cadmium sulfide (CdS) by solution process and successfully obtained CdS/ZnO core–shell nanofibers. The CdS modification at the optimum condition can dramatically improve all photovoltaic parameters and increase the power conversion efficiency of the hybrid solar cells for over 100%. In addition, the lifetimes of carriers in the hybrid solar cells characterized by impedance analyzer become much longer after the modification of CdS. The effect of CdS modification on the devices can be mainly attributed to the cascaded energy band structure of the heterojunction that favors charge transport process and thus increases the efficiencies of the devices.     

晶体硅太阳电池的双层结构钝化膜研究

针对目前基于p型硅片制备的单结太阳电池进一步提高表面钝化膜生产效率,利用氮化硅(SiNx)薄膜良好的钝化效果与价格低廉的二氧化钛(TiO2)膜,降低SiNx镀膜厚度减薄对少子寿命的影响。在单晶硅片表面先用PECVD法沉积SiNx薄膜,然后用热喷涂沉积TiO2薄膜。对比测试了热喷涂沉积TiO2薄膜前后电池的性能,结果表明在SiNx膜上增加TiO2膜层后少子寿命明显提高,这可能是TiO2膜结构内存在固定正电荷所致。这种双层结构封装后的太阳电池显示出了较好的光学与电学性能,对进一步改进太阳电池性能具有重要参考价值。     

Factors Affecting the Stability of CdTe/CdS Solar Cells Deduced from Stress Tests at Elevated Temperature

CdTe/CdS solar cells were subjected to heat stress at 200 °C in the dark under different environments (in N₂ and in air), and under illumination (in N₂). We postulate that two independent mechanisms can explain degradation phenomena in these cells: i) Excessive Cu doping of CdS: Accumulation of Cu in the CdS with stress, in the presence of Cl, will increase the photoconductivity of CdS. With limited amounts of Cu in CdS, this does NOT affect the photovoltaic behavior, but explains the crossover of light/dark current–voltage (J–V) curves. Overdoping of CdS with Cu can be detrimental to cell performance by creating deep acceptor states, acting as recombination centers, and compensating donor states. Under illumination, the barrier to Cu cations at the cell junction is reduced, and, therefore, Cu accumulation in the CdS is enhanced. Recovery of light‐stress induced degradation in CdTe/CdS cells in the dark is explained by dissociation of the acceptor defects. ii) Back contact barrier: Oxidation of the CdTe back surface in O₂/H₂O‐containing environment to form an insulating oxide results in a back‐contact barrier. This barrier is expressed by a rollover in the J–V curve. Humidity is an important factor in air‐induced degradation, as it accelerates the oxide formation. Heat treatment in the dark in inert atmosphere can stabilize the cells against certain causes of degradation, by completing the back contact anneal.