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。     

CH3NH3PbI3/p-Si异质结的光电特性研究

利用一步溶液法在p型Si衬底上生长有机/无机杂化钙钛矿CH3NH3PbI3薄膜,构成CH3NH3PbI3/p-Si异质结。利用原子力显微镜(AFM)、扫描电子显微镜(SEM)对薄膜形貌和结构进行表征,通过无光照和有光照条件下的电流-电压(I-V)、电容-电压(C-V)测试对异质结的光电特性进行研究。I-V测试结果显示CH3NH3PbI3/p-Si异质结具有整流特性,正反偏压为±5V时,整流比大于70,并在此异质结上观察到了光电转换现象,开路电压为10mV,短路电流为0.16uA。C-V测试结果显示Ag/CH3NH3PbI3/p-Si异质结具有与MIS(金属-绝缘层-半导体)结构相似的C-V特性曲线,与理想MIS的C-V特性曲线相比,异质结的C-V曲线整体沿电压轴向正电压方向平移。C-V特性曲线的这种平移表明Ag/CH3NH3PbI3/p-Si异质结界面存在界面缺陷,CH3NH3PbI3层也可能存在固定电荷。这种界面缺陷是导致CH3NH3PbI3/p-Si异质结开路电压的大幅度降低的重要原因。此外,CH3NH3PbI3薄膜的C-V测试结果显示其具有介电非线性特性,其介电常数约为4.64。     

Cl掺杂对n-Cu2O的光电性能的影响

在酸性溶液中利用恒电位沉积法在导电玻璃(ITO)上沉积Cu2O薄膜,并以KC1为添加剂对其进行掺杂,采用场发射扫描电子显微镜(FESEM)和X射线衍射谱(XRD)等手段研究了氯掺杂对Cu2O表面形貌和晶体结构的影响.紫外-可见吸收光光谱确定得到的Cu2O和Cl掺杂Cu2O(Cu2 O-C1)样品的禁带宽度分别为1.98和1.95 eV.根据表面光电压谱和相位谱,掺杂前后的Cu2O均为n型,Cu2 O-C1有更强的表面光电压响应.场诱导表面光电压谱结果表明未掺杂C1的Cu2O在加负偏压时易形成反型层;氯离子的掺杂引入杂质能级可以提高n型导电性.光电化学性能测试发现,以Cu2O、Cu2 O-Cl为光阳极组成的光化学太阳电池,在大气质量AM 1.5G、100 mW/cm2标准光强作用下光电转换效率分别为0.12％和0.51％.     

Sb2S3/TiO2纳米管异质结阵列的制备和光电性能

结合水热法和阳极氧化法合成了Sb2S3/TiO2纳米管异质结阵列,采用场发射扫描电子显微镜、X射线衍射谱表征了异质结阵列的形貌和晶体结构.暗态下的电流-电压曲线表明Sb2S3/TiO2纳米管异质结阵列具有整流效应.相比于纯的TiO2纳米管阵列,Sb2S3/TiO2纳米管异质结阵列的光电性能有了显著地提升:在AM1.5标准光强作用下,光电转换效率从0.07％增长到0.40％,表面光电压响应范围从紫外光区拓宽至可见光区.结合表面光电压谱和相位谱,分析了Sb2S3/TiO2纳米管异质结阵列中光生载流子的分离和传输性能.     

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.     

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。     

Sb2O3掺杂对ZnO薄膜光吸收性能的影响

采用RF磁控溅射技术制备了Sb2O3掺杂ZnO薄膜,通过X射线光电子能谱仪（XPS）、X射线衍射仪（XRD）和紫外-可见光（UV-Vis）分光光度计研究了Sb2O3对ZnO薄膜结构和光吸收性能的影响。结果表明：Sb2O2的掺杂影响了ZnO的原子和电子状态、晶粒的生长方式和光吸收性能。薄膜中Sb以多种形态存在：替位原子和化合物（Sb2O3、Zn,Sb2O14）等,ZnO呈混晶方式生长;随着Sb含量的增加,其引起的晶格畸变和次晶相的含量逐渐增加;掺杂薄膜在远紫外（UVA）波段的吸收显著增强,UV吸收峰变窄,强度增大,吸收边变得陡峭且向短波方向移动达5nm,在Vis波段的吸收有所增强。     

掺杂Sm_2O_3对BaSrTiO_3介电陶瓷性能的影响

以碳酸钡、碳酸锶和二氧化钛等为原料,Sm2O3为掺杂剂,制备了BaSrTiO3系介质陶瓷。利用SEM等仪器研究了陶瓷试样的微观形貌和介电性能。结果表明:当Sm2O3掺杂量低于0.10%摩尔分数时,Sm3+进入晶格A位;但随着Sm2O3掺杂量的增加,Sm3+越来越倾向于进入晶格B位。在Sm2O3掺杂量为摩尔分数0.10%时,BaSrTiO3陶瓷的相对介电常数达到最高值4800;随着Sm2O3掺杂量继续增加,陶瓷的介电损耗逐渐降低,最低降至0.0070。     

Ce掺杂Bi2S3/Fe2O3异质结的制备及其光电性能

采用旋涂法与水热法在掺氟二氧化锡(FTO)上制备了Ce掺杂Bi2S3/Fe2O3(Ce-Bi2S3/Fe2O3)异质结,对样品的组成、形貌及其光电性能进行了研究分析.结果 显示,Ce-Bi2S3/Fe2O3的X射线衍射(XRD)图谱中各衍射峰位与Bi2S3/Fe2O3相似,无新的相产生,但在2θ为24.92°(130)与28.65°(211)的衍射峰强度有所降低,而在2θ为35.65°(110)时有所增强;在Ce-Bi2S3/Fe2O3的X射线能谱(EDS)中发现了Ce元素.光电性能测试结果表明,在模拟太阳光的照射下Ce-Bi2S/Fe2O3的光电压为0.347 V,比Bi2S3/Fe2O3 (0.281 V)提高了23.5％;光电流密度达到2.31 mA·cm-2,比Bi2S3/Fe2O3 (0.53 mA·cm-2)提高了约3.36倍;电化学阻抗谱(EIS)显示,在光照下Ce-Bi2S3/Fe2O3具有最低的界面阻抗,表明Ce-Bi2S3/Fe2O3中的载流子被更有效地分离和转移.     

Self-Assembled Perovskite Nanoislands on CH3NH3PbI3 Cuboid Single Crystals by Energetic Surface Engineering

Organometal perovskite single crystals have been recognized as a promising platform for high-performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal-based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet-controlled cuboid MAPbI₃ (MA = CH₃NH₃⁺) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs-Pb-rich nanoislands is constructed on the surface of the MAPbI₃ single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm² V⁻¹ s⁻¹. As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high-quality perovskite single-crystal surface for optoelectronic applications.     

A promising unisource thermal evaporation for in situ fabrication of organolead halide perovskite CH3NH3PbI3 thin film

In this work, a new method of fabricating organolead halide perovskite CH₃NH₃PbI₃ thin film by unisource thermal evaporation was proposed, which ensured high‐quality film with composition, crystal‐structure homogeneity, full surface coverage, well‐defined grain structure, high crystalline, and reproducibility, suggesting its promising applicability for significant optimization in efficient. Copyright © 2015 John Wiley & Sons, Ltd.     

Deciphering the NH4PbI3 Intermediate Phase for Simultaneous Improvement on Nucleation and Crystal Growth of Perovskite

The NH₄PbI₃‐based phase transformation is realized by simply adding NH₄I additive, in order to simultaneously control perovskite nucleation and crystal growth. Regarding the nucleation process, the NH₄⁺ with small ionic radius preferentially diffuses into the [PbI₆]^4? octahedral layer to form NH₄PbI₃, which compensates the lack of CH₃NH₃I (MAI) precipitation. The generation of NH₄PbI₃ intermediate phase results in extra heterogeneous nucleation sites and reduces the defects derived from the absence of MA⁺. Regarding the crystal growth process, the cation exchange process between MA⁺ and NH₄⁺, instead of the MAs directly entering, successfully retards the crystal growth. Such NH₄PbI₃ consumption process slows down the crystal growth, which effectively improves the perovskite quality with lowered defect density. The cooperation of these two effects eventually leads to the high‐quality perovskite with enlarged grain size, prolonged photoluminescence lifetime, lowered defect density, and increased carrier concentration, as well as the finally enhanced photovoltaic performance. Moreover, NH₃ as a byproduct further facilitates the proposed transformation process and no external residue remains even without any post‐treatment. Such methodology of introducing a novel phase transformation to simultaneously control nucleation and crystal growth processes is of universal significance for further devotion in the foreseeable perovskite solar cells (PSCs) evolution.     

Nonlinear Absorption Applications of CH3NH3PbBr3 Perovskite Crystals

Researchers have recently revealed that hybrid lead halide perovskites exhibit ferroelectricity, which is often associated with other physical characteristics, such as a large nonlinear optical response. In this work, the nonlinear optical properties of single crystal inorganic–organic hybrid perovskite CH₃NH₃PbBr₃ are studied. By exciting the material with a 1044 nm laser, strong two‐photon absorption‐induced photoluminescence in the green spectral region is observed. Using the transmission open‐aperture Z‐scan technique, the values of the two‐photon absorption coefficient are observed to be 8.5 cm GW^?1, which is much higher than that of standard two‐photon absorbing materials that are industrially used in nonlinear optical applications, such as lithium niobate (LiNbO₃), LiTaO₃, KTiOPO₄, and KH₂PO₄. Such a strong two‐photon absorption effect in CH₃NH₃PbBr₃ can be used to modulate the spectral and spatial profiles of laser pulses, as well as to reduce noise, and can be used to strongly control the intensity of incident light. In this study, the superior optical limiting, pulse reshaping, and stabilization properties of CH₃NH₃PbBr₃ are demonstrated, opening new applications for perovskites in nonlinear optics.     

Layered (C6H5CH2NH3)2CuBr4 Perovskite for Multilevel Storage Resistive Switching Memory

Although there have been attempts to use non‐lead based halide perovskite materials as insulating layers for resistive switching memory, the ratio of low resistance state (LRS) to high resistance state (HRS) ( = ON/OFF ratio) and/or endurance is reported to be mostly lower than 10³. Resistive switching memory characteristics of layered (BzA)₂CuBr₄ (BzA = C₆H₅CH₂NH₃) perovskite with high ON/OFF ratio and long endurance are reported here. The X‐ray diffraction (XRD) pattern of the deposited (BzA)₂CuBr₄ layer shows highly oriented (00l) planes perpendicular to a Pt substrate. An Ag/PMMA/(BzA)₂CuBr₄/Pt device shows bipolar switching behavior. A forming step at around +0.5 V is observed before the repeated bipolar switching at the SET voltage of +0.2 V and RESET voltage of ‐0.3 V. The ON/OFF ratio as high as =10⁸ is monitored along with an endurance of ≈2000 cycles and retention time over 1000 s. The high ON/OFF ratio enables multilevel storage characteristics as confirmed by changing the compliance currents. Ohmic conduction at the LRS and Schottky emission at HRS are involved in electrochemical metallization process. The bipolar resistive switching property is retained after storing the device at ambient condition under relative humidity of about 50% for 2 weeks, which indicates that (BzA)₂CuBr₄ is stable memory material.     

Synergistic Effect of PbI2 Passivation and Chlorine Inclusion Yielding High Open‐Circuit Voltage Exceeding 1.15 V in Both Mesoscopic and Inverted Planar CH3NH3PbI3(Cl)‐Based Perovskite Solar Cells

Enhancing open‐circuit voltage in CH₃NH₃PbI₃(Cl) perovskite solar cells has become a major challenge for approaching the theoretical limit of the power conversion efficiency. Here, for the first time, it is demonstrated that the synergistic effect of PbI₂ passivation and chlorine incorporation via controlling the molar ratio of PbI₂, PbCl₂ (or MACl), and MAI in the precursor solutions, boosts the open‐circuit voltage of CH₃NH₃PbI₃(Cl) perovskite solar cells over 1.15 V in both mesoscopic and inverted planar perovskite solar cells. Such high open‐circuit voltage can be attributed to the enhanced photoluminescence emission and carrier lifetime associated with the reduced trap densities. The morphology and composition analysis using scanning electron microscopy, X‐ray diffraction measurements, and energy dispersive X‐ray spectroscopy confirm the high quality of the optimized CH₃NH₃PbI₃(Cl) perovskite film. On this basis, record‐high efficiencies of 16.6% for nonmetal‐electrode all‐solution‐processed perovskite solar cells and 18.4% for inverted planar perovskite solar cells are achieved.