PbI2掺杂对CH3NH3PbI3光电性能的影响

采用溶液生成法制备了有机铅卤化钙钛矿(CH3 NH3PbI3)晶体粉末,并以过量的PbI2对其进行掺杂,采用X射线衍射谱(XRD)技术研究了掺杂前后样品的晶体结构变化.表面光电压谱(SPS)和相位谱(PS)显示掺杂前后的CH3 NH3 PbI3均为p型半导体,但后者有更强的光伏响应.场诱导表面光电压谱(FISPS)表明:当加正电场时,掺杂前后的CH3NH3PbI3均表现为p型半导体的载流子特性,当加负偏压时掺杂后的CH3NH3PbI3易形成反型层,出现光伏反转,且外加负偏压越大,光伏反转区域越大,表现出双极导电特性.     

CH3NH3PbI3钙钛矿太阳电池晶粒尺寸及光电性能调控

钙钛矿薄膜的晶粒尺寸对器件性能影响很大。采用湿润性不同的空穴传输层以及不同浓度的CH3NH3I（MAI）溶液,使用热退火和溶剂气氛退火的方法制备出CH3NH3PbI3薄膜及相应电池。测量了不同制备条件的钙钛矿薄膜的X射线衍射、扫描电子显微镜、光致发光谱,以及器件的电流密度-电压曲线。结果表明,溶剂气氛退火可以有效地增大薄膜的晶粒尺寸,提高器件的电流密度;较高浓度的MAI能将PbI2完全转化为CH3NH3PbI3,增大晶粒尺寸;不湿润的功函数更高的空穴传输层有利于电池效率的提高。制备了最高效率为13.3%的CH3NH3PbI3钙钛矿电池,为制备更大晶粒的钙钛矿薄膜与更高效率的钙钛矿太阳电池奠定了基础。     

ZnO/p-Si异质结的I-V及C-V特性研究

通过磁控溅射Al掺杂的ZnO陶瓷靶,在p-Si片上沉积n型电导的ZnO薄膜而制备了ZnO/p-Si异质结,并通过测试其光照下的I-V、C-V特性对其光电特性以及载流子输运特性与导电机理进行了研究。研究表明ZnO/p-Si异质结存在良好的整流特性与光电响应,可以广泛应用在光电探测和太阳电池等领域。由于在ZnO/p-Si异质结界面处的导带补偿与价带补偿相差太大的缘故,在正向电压超过1V时,导电机理为空间电荷限制电流导电。同时,研究表明ZnO/p-Si异质结界面存在大量界面态,可以通过减小界面态进一步提高其光电特性。     

射频磁控溅射法制备AZO/p-Si异质结及其性能研究

利用射频磁控溅射法,在p-Si衬底上生长了Al掺杂的ZnO(AZO)薄膜,并进而制备了AZO/p-Si异质结。X射线衍射仪、紫外-可见光分光光度计、四探针测试仪和霍尔效应测试仪测量表明,AZO薄膜具有良好的结晶质量、光学和电学特性。暗态下的I-V测试表明,AZO/p-Si异质结具有较好的整流特性,反向饱和电流为1.29×10-6A,±2V处的正向和反向电流之比为229.41,计算得出异质结的理想因子为2.28。在标准光照下AZO/p-Si异质结呈现出明显的光生伏特效应,这种异质结太阳电池具有2.51%的光电转换效率。     

n-Si/p-CuI异质结的制备及其光电特性研究

采用成本低廉的连续离子层沉积法通过在n型Si衬底上沉积γ相的多晶结构的CuI薄膜而制备了CuI/n-Si异质结。并通过测试其光照下的I-V、C-V特性对其光电特性、载流子输运特性及导电机理进行了研究。研究表明CuI/n-Si异质结存在良好的整流特性,由于在CuI/nSi异质结界面处的导带补偿与价带补偿相差较大,在正向电压、无光照下,导电机理为空间电荷限制电流导电,此时空穴电流主导;在光照下,异质结表现出良好的光电响应,因此可以广泛应用在光电探测和太阳电池等领域。     

高效硅基异质结太阳能电池的模拟

a-Si:H/c-Si异质结太阳能电池的基本参数,如层厚度、掺杂浓度、a-Si:H/c-Si界面缺陷、功函数等是影响载流子传输特性和电池效率的关键因素。在本文中,利用AFORS-HET程序,研究了这些参数与a-Si:H/c-Si电池的性能的关联性。最后,具有TCO/n-a-Si:H/i-a-Si:H/p-c-Si/p -a-Si:H/Ag结构的太阳能电池的最优化性能被获得,其光电转换效率为27.07%（VOC: 749 mV, JSC: 42.86 mA/cm2, FF: 84.33%）。深入地了解异质结电池的输运特性,对进一步提高电池的效率有很大的帮助,同时对实际太阳能电池的制造也能提供有益的指导。     

CH3 CSNH2/NH4 OH钝化GaInAsSb/GaSb PIN红外探测器

引入一种新的低毒化合物CH3CSNH2/NH 4OH对GaInAsSb化合物探测器的表面进行了钝化处理,可使其暗电流降低一个数量级,动态电阻增大25倍多,且钝化83天后保持良好的钝化效果,取得了与(NH4)2S溶液一样理想的钝化效果.并采用AES和XPS对钝化前后的GaInAsSb材料进行了分析.     

CH3CSNH2/NH4OH钝化GaInAsSb/GaSb PIN红外探测器

引入一种新的低毒化合物CH3CSNH2/NH4OH对 GaInAsSb化合物探测器的表面进行了钝化处理，可使其暗电流降低一个数量级，动态电阻增大25倍多，且钝化83天后保持良好的钝化效果，取得了与（NH4)2S溶液一样理想的钝化效果. 并采用AES和XPS对钝化前后的GaInAsSb材料进行了分析.     

无坑洞n-3C-SiC/p-Si(100)的LPCVD外延生长及其异质结构特性

在MBE/CVD高真空系统上,利用低压化学气相淀积(LPCVD)方法在直径为50mm的单晶Si(100)衬底上生长出了高取向无坑洞的晶态立方相碳化硅(3C-SiC)外延材料,利用反射高能电子衍射(RHEED)和扫描电镜(SEM)技术详细研究了Si衬底的碳化过程和碳化层的表面形貌,获得了制备无坑洞3C-SiC/Si的优化碳化条件,采用霍尔(Hall)测试等技术研究了外延材料的电学特性,研究了n-3C-SiC/p-Si异质结的I-V、C-V特性及I-V特性对温度的依赖关系.室温下n-3C-SiC/p-Si异质结二极管的最大反向击穿电压达到220V,该n-3C-SiC/p-Si异质结构可用于制备宽带隙发射极SiC/Si HBTs器件.     

无坑洞n-3C-SiC/p-Si(100)的LPCVD外延生长及其异质结构特性

在MBE/CVD高真空系统上,利用低压化学气相淀积( L PCVD)方法在直径为5 0 mm的单晶Si( 10 0 )衬底上生长出了高取向无坑洞的晶态立方相碳化硅( 3 C- Si C)外延材料,利用反射高能电子衍射( RHEED)和扫描电镜( SEM)技术详细研究了Si衬底的碳化过程和碳化层的表面形貌,获得了制备无坑洞3 C- Si C/Si的优化碳化条件,采用霍尔( Hall)测试等技术研究了外延材料的电学特性,研究了n- 3 C- Si C/p- Si异质结的I- V、C- V特性及I- V特性对温度的依赖关系.室温下n- 3 C- Si C/p- Si异质结二极管的最大反向击穿电压达到2 2 0 V,该n- 3 C- Si C/p- Si异质结构可用于制     

A simple fabrication of CH3NH3PbI3 perovskite for solar cells using low-purity PbI2

The CH₃NH₃PbI₃ (MAPbI₃) perovskite was usually prepared by high-purity PbI₂ with high cost. The low cost and low-purity PbI₂ was seldom reported for fabrication of MAPbI₃ because it cannot even dissolve well in widely adopted solvent of DMF. We developed an easy method to adapt low-purity PbI₂ for fabrication of high quality MAPbI₃ just by the simple addition of some hydrochloric acid into the mixture of low-purity PbI₂, MAI and DMF. This straightforward method can not only help dissolve the low quality PbI₂ by reacting with some impurities in DMF, but also lead to a successful fabrication of high-quality perovskite solar cells with up to 14.80% efficiency comparable to the high quality PbI₂ precursors.     

A methylammonium iodide healing method for CH3NH3PbI3 perovskite solar cells with high fill factor over 80%

Repressing the thermal decomposition during the process of heat treatment plays an indispensable part in the preparation of perovskite films. Here, a methylammonium iodide healing method was applied to prevent the volatilization of the organic component inside the perovskite structure during the heat treatment. High-quality CH₃NH₃PbI₃ film with a much larger grain size over 800 nm was successfully fabricated via this healing method. Besides, the absorption and photoluminescence intensity were also both improved. Finally, the best power conversion efficiency of 18.89% with a fill factor over 80% was realized in an n–i–p configuration while possessing outstanding stability. This work suggests that methylammonium iodide healing method is a reliable way to promote crystal growth and improve the photovoltaic performance and humidity stability of the CH₃NH₃PbI₃ solar cells.     

溶剂热处理法制备的钙钛矿CH3NH3PbI3薄膜的微观形貌与电池性能的研究

近年来研究表明,通过增大晶粒尺寸和减少晶界数量可以有效减小钙钛矿太阳能电池的漏电流和增大并联电阻,极大地增加其能量转化效率。溶剂热处理工艺是一种利用溶解再结晶的原理增大薄膜晶粒的实用工艺,可用于制备大晶粒高质量的多晶薄膜。本文制备了不同溶剂热处理时长的旋涂制备的钙钛矿CH₃NH₃PbI₃薄膜,利用SEM和XRD分析了其形貌和晶体结构的变化,探索了薄膜晶粒形貌与电池性能的对应关系,应用优化后的溶剂热处理工艺成功制备出大晶粒、高性能的钙钛矿薄膜。实验表明,溶剂热处理法制备的钙钛矿CH₃NH₃PbI₃薄膜平均晶粒尺寸接近3μm,较普通热处理方法制备的薄膜晶粒尺寸(约300 nm)有显著增大。     

WO3/SnO2复合薄膜的制备及光电性能

采用水热法和电化学沉积法,成功制备了包覆有SnO₂纳米颗粒的WO₃纳米棒阵列薄膜,退火处理后形成WO₃/SnO₂异质结复合薄膜。通过改变SnO₂的沉积时间得到了复合薄膜的最佳制备条件。采用XRD,FESEM对WO₃/SnO₂复合薄膜的物相和形貌进行了分析,通过电化学工作站对WO₃/SnO₂复合薄膜的光电性能进行了研究,结果表明,电沉积时间为120 s时,WO₃/SnO₂复合薄膜具有最小的阻抗,且在0.6 V的偏压下光电流密度为0.46 mA/cm²,相比于单一WO₃纳米棒薄膜,表现出更好的光电化学性能。     

GaInP2/Ge异质结外延材料特性分析

研制了一种基于Ge衬底的异质结热光伏(TPV)电池 ,并且在Ge衬底上用金属有机化学气相沉积(MOCVD)法外延单晶材料GaInP₂和GaAs,对GaInP₂/Ge异质结界面进行了断面扫描电镜(SEM)、X射线衍射(XRD)、电化学电 容电压(ECV)和光致荧光(PL)谱的测试分析,研究了基于 Ge衬底的异质结n-GaInP₂/p-Ge界面的结构、光学和电学特性,得到了高质量、宽禁带 的单晶外延层,与Ge衬底晶格匹配良好,利于更多光子进入到吸收层,为制备高效率TPV电 池打下良好基础。     

Co3O4/Fe2O3异质结复合材料的制备及其紫外光光电探测性能

分别采用旋涂法和水热法在FTO衬底上制备Co₃O₄种子层和Co₃O₄薄膜,再在Co₃O₄薄膜上水热生长Fe₂O₃纳米棒,获得了高质量的Co₃O₄/Fe₂O₃异质结复合材料。通过改变Fe₂O₃前驱体溶液浓度来改变异质结复合材料中Fe₂O₃组分的含量。结果表明,Fe₂O₃纳米棒覆盖在呈网状结构的Co₃O₄薄膜上,随着Fe₂O₃前驱体溶液浓度即Fe₂O₃组分含量的增加,Co₃O₄/Fe₂O₃异质结复合材料对紫外光的响应逐渐增强,当Fe₂O₃前驱体溶液浓度为0.015mol/L时,异质结复合材料有着很好的光电稳定性,并表现出较高的响应率(12.5mA/W)和探测率(4.4×10¹⁰Jones)。     

介稳态TiCl4醇水溶液水解制备TiO2致密层及其在无机-有机杂化异质结钙钛矿太阳电池中的应用

致密层作为钙钛矿太阳电池的重要组成部分, 对其制备方法, 工艺及微结构等性质的研究对提高钙钛矿太阳电池的光伏性能具有重要影响. 本文利用介稳态的TiCl₄醇水溶液作为前驱体溶液, 通过旋涂水解制备TiO₂致密层, 并研究了前驱体溶液不同醇水比对致密层微结构及其相应太阳电池光伏性能的影响. 结果表明, 将2 mol.L_-1的TiCl₄的水溶液按醇水体积比3:1的比例用异丙醇稀释后所制备的TiO₂致密层其厚度为126 nm, 且相应的太阳电池取得最高的光电转换效率10.6 %.     

Simulation approach for optimization of ZnO/c-WSe2 heterojunction solar cells

Taking into account defect density in WSe₂, interface recombination between ZnO and WSe₂, we presented a simulation study of ZnO/crystalline WSe₂ heterojunction (HJ) solar cell using wxAMPS simulation software. The optimal conversion efficiency 39.07% for n-ZnO/p-c-WSe₂ HJ solar cell can be realized without considering the impact of defects. High defect density (> 1.0 × 10¹¹ cm^-2) in c-WSe₂ and large trap cross-section (> 1.0 × 10^-10 cm²) have serious impact on solar cell efficiency. A thin p-WSe₂ layer is intentionally inserted between ZnO layer and c-WSe₂ to investigate the effect of the interface recombination. The interface properties are very crucial to the performance of ZnO/c-WSe₂HJ solar cell. The affinity of ZnO value range between 3.7-4.5 eV gives the best conversion efficiency.     

Performance analysis of 20 nm gate-length In0.2Al0.8N/GaN HEMT with Cu-gate having a remarkable high ION/IOFF ratio

Abstract： We propose a new structure of InxAll-xN/GaN high electron mobility transistor （HEMT） with gate length of 20 nm. The threshold voltage of this HEMT is achieved as -0.472 V. In this device the InA1N barrier layer is intentionally n-doped to boost the ION/IOFF ratio. The InAlN layer acts as donor barrier layer for this HEMT which exhibits an ION = 10-4.3 A and a very low IOFF = 10-14.4 A resulting in an ION/IoFF ratio of 1010.1. We compared our obtained results with the conventional InAlN/GaN HEMT device having undoped barrier and found that the proposed device has almost l0s times better ION/IOFF ratio. Further, the mobility analysis in GaN channel of this proposed HEMT structure along with DC analysis, C-V and conductance characteristics by using small-signal analysis are also presented in this paper. Moreover, the shifts in threshold voltage by DIBL effect and gate leakage current in the proposed HEMT are also discussed. InAlN was chosen as the most preferred barrier layer as a replacement of AlGaN for its excellent thermal conductivity and very good scalability.     

The electronic structures and optical properties of BaTiO3 and SrTiO3 using first-principles calculations

The electronic-energy band structures and total density of states (TDOS) for bulk BaTiO₃ and SrTiO₃ were calculated by the first-principles calculations using density-functional theory and local-density approximation. The calculated band structure of BaTiO₃ and SrTiO₃ show the energy band gaps of 1.81 and 1.92 eV at the Γ point in the Brillouin zone, respectively. The optical properties of the both perovskites in the core-level spectra are investigated by the first principles under scissor approximation. The optical constants like refractive index and extinction coefficient of both BaTiO₃ and SrTiO₃ were derived from the calculated real and imaginary parts of the dielectric function. The calculated spectra were compared with the experimental results for BaTiO₃, SrTiO₃ in good agreement.