基于传输矩阵法的聚合物太阳能电池光学性能分析

采用基于传输矩阵法的光学模型及Matlab软件,模拟了以聚合物P3HT:PCBM为活性层的倒装太阳能电池,并分析了模拟电池的吸光率及其内部光电场分布。探讨了厚度、入射角度以及新结构对电池光学性能的影响。模拟结果表明,电池的光吸收主要由活性层厚度决定,分别随着电子传输层和空穴传输层厚度的增加而下降。当光入射角度增大时,由于光程的增加电池的吸光率随之增加,在40°入射角时达到最大;由于其他光学作用,器件吸光率在40°入射角以后反而降低;证明了光斜入射时电场在整个器件中分布是不连续的。通过在基本结构的适当位置插入一层薄膜构成的微腔器件,由于光学共振效应能够有效提高电池的光吸收。     

镀膜法改善有机薄膜太阳能电池光学性能

有机活性材料的低载流子迁移率使得有机光伏电池的电极收集到的电荷较少。增加活性层光吸收能够增加激子的产生数从而增加电极收集到的电荷,提升器件的性能。通过对器件模拟的方法,研究以P3HT：PCBM为活性层的薄膜太阳能电池的光学性能。 在此基础上,提出采用镀多层高反射膜的方法改善电池器件的光学性能。结果表明：活性层厚度对电池器件的光吸收起到主导作用;镀多层高反射膜在活性层厚度小于160 nm、Ag厚度小于20 nm时能大幅度改善电池器件的光学性能,光生激子总数随活性层厚度的增加而迅速增多,并且在活性层厚度约为150 nm时为一个最佳值。     

基于相变原理模拟红色顶发射有机电致发光器件的出光性能

研究了有机发光器件(organic light emitting diodes, 简记为OLED)半透明电极上形成的反射相移对OLED光谱产生调制现象.以红色微腔结构顶发射OLED(top emitting OLED,TOLED)为例,基于微腔理论和传输矩阵理论建立物理模型,采用计算机数值模拟方法,得出结果表明器件发光光谱的调制作用不只局限于有机层厚度,也和反射相移有关.通过改变覆盖到顶电极表面的有机层厚度的简单方法,可以实现对顶电极反射相移的调节,从而改变TOLED光学性能.这一结果为进一步改善器件的性 关键词： 反射相移模拟 红色微腔 顶发射有机发光     

基于Ag/Ge/Ag阳极的as

通过在Ag层中引入一层Ge薄膜, 获得了具有低反射率和高反射相移的Ag/Ge/Ag复合阳极, 并制备了基于该阳极的蓝光顶发射有机电致发光器件.阳极高的反射相移使得器件在有机层厚度为100 nm时获得了顶发射蓝光发射, 且阳极较低的反射率减弱了器件内的微腔效应, 使得其电致发光光谱在不同视角下具有良好的稳定性.当Ge的厚度为20 nm时, 器件性能表现最为优良, 最高亮度和最大电流效率分别可达3 612 cd/m²和5.4 cd/A, 且色坐标在视角从0°变化到60°时仅移动了(0.007, 0.006).     

硅基薄膜太阳电池一维光子晶体背反射器的模拟设计与制备

从模拟和实验两个方面研究了一种适用于硅基薄膜太阳电池的一维光子晶体新型背反射器.首先采用时域有限差分方法,模拟研究了组成一维光子晶体的两种介质的折射率比、厚度比以及周期厚度对光子禁带的影响.基于模拟结果,制备出一种由低折射率SiOx层与高折射率非晶硅a-Si层周期性交叠构成的禁带可调式一维光子晶体背反射器.通过改变a-Si层的厚度,使得禁带范围由500—750 nm波长范围红移至650—1100 nm,反射率分别达到96.4%和99%.将上述结构的一维光子晶体作为背反射器分别应用于非晶硅单结太阳电池和非晶硅/微晶硅双结叠层太阳电池,与没有背反射结构电池相比,短路电流密度分别提升了18.3%和15.2%.同时模拟研究了在不同入射角度下自然光、TE波和TM波对光子晶体反射特性的影响.研究结果表明,在太阳电池中,光线倾斜入射对一维光子晶体反射率的影响有限.     

钙钛矿/硅异质结叠层太阳电池:光学模拟的研究进展

近几年,钙钛矿/硅异质结叠层太阳电池发展迅速,效率已经从13.7%提升到29.1%.由于叠层电池器件的制作工艺复杂,而叠层太阳电池中的光学损失对转换效率的影响很大,所以通过光学模拟进而获得高效电池至关重要.本文首先从商业软件和自建模型两方面概述了光学模拟的方法,接着从反射损失和寄生吸收两方面针对光学模拟研究进展进行了总结和分析,最后指出了叠层电池光学模拟过程中需要注意的问题.钙钛矿/硅异质结叠层太阳电池的转换效率极限最高可达40%,具备很大的提升空间,结合模拟工作的研究,叠层电池的发展将会取得更大的进步.     

Ge0.05Si0.95/Si异质结单模共面布拉格反射波导光栅的设计与分析

GeSi/Si异质结布拉格反射光栅是硅基光电集成领域一种重要的集成光学器件,分析GeSi/Si异质结的传光特性和布拉格条件,通过求解布拉格光栅方程,得出耦合系数和耦合效率。利用上述原理设计出入射角为66°,波导层的厚度为2μm,光栅长度为4252μm,槽深为0.05μm,光栅周期为0.456μm,滤波带宽为0.214nm,耦合效率为84.1%的1.3μm Ge_0.05Si_0.95/Si异质结单模共面布拉格反射光栅,并用数值模拟了入射光波电场和反射光波电场的分布。     

光子晶体异质结的位相和应用

研究了由不同周期结构的光子晶体组成的异质结和含耦合杂质的光子晶体异质结的位相. 发现光子晶体异质结使光子晶体杂质模的反射率接近1,但反射相移不随反射率的改变而改变,反射相移只由前边的子光子晶体的禁带、通带或耦合杂质模中的子峰决定. 即异质结的前边的子光子晶体的耦合杂质模中的每一子峰、每一通带或禁带对应的反射相移为2π. 对多杂质耦合的结构,反射相移很灵敏,可用于制作高灵敏光子器件. 以全光位相与非门为例描述全光位相逻辑门的方案和可行性. 另外,这些特性对研究位相有关的新物理过程和现象有意义. 关键词： 光子晶体 位相 异质结 耦合杂质     

结构参数对p-i-n结构InGaN太阳能电池性能的影响及机理

研究了器件结构参数对p-i-n结构InGaN单结太阳能电池性能的影响及物理机制. 模拟结果发现: 随着InGaN禁带宽度的增加, InGaN电池的短路电流减小, 但同时开路电压增加, 当InGaN层的禁带宽度为1.5 eV左右时, 同质p-i-n结InGaN电池的效率最高, 并计算了不同厚度的i层对InGaN电池效率的影响. 进一步的计算表明, 适当采用带宽更大的p-InGaN层形成异质p-i-n结InGaN电池可以获得更高效率, 但是p-InGaN层带宽过大也会导致电池的效率急剧下降. 研究还发现, 采用禁带宽度更大的n-InGaN层可以形成背电场, 从而增加p-i-n结InGaN太阳电池的效率. 研究结果表明, 适当选择p-InGaN和n-InGaN禁带宽度形成异质p-i-n结可以提高InGaN太阳能电池效率.     

氧化锌掺铝绒面薄膜在有机光伏电池中的应用

目前有机光伏电池的吸光活性层电学传输特性和光学吸收特性的不匹配是制约其能量转换效率提升的主要原因之一. 通过陷光结构对入射光进行调控, 提高电池对光的约束和俘获能力从而达到“电学薄”和“光学厚”的等效作用, 是解 决有机光伏电池电学和光学不匹配的有效手段. 本文采用湿法刻蚀技术获得了系列时间梯度的绒面氧化锌掺铝薄膜, 并将其作为有机光伏电池的入射陷光电极, 显著增强了电池的光学吸收. 研究发现, 当使用浓度0.5%的稀HCL腐蚀30 s后的氧化锌掺铝薄膜作为入射电极后, 电池的光电性能和效率显著增强. 基于此绒面电极电池的电流密度比平面结构的电池提高了8.17%, 效率改善了11.29%. 通过对绒面电极表面的修饰处理, 实现了电极与光活性层之间良好的界面接触, 从而减小了对电池的开路电压和填充因子的影响.     

ZnO/Ag/ZnO multilayer transparent electrode for highly-efficient ITO-Free polymer solar cells

Ultrathin metal film (UTMF) with a ZnO/Ag/ZnO hybrid structure was used as transparent electrode in a high-efficiency bulk heterojunction system for the fabrication of ITO-free polymer solar cells. The performance of the devices was carefully tuned through optical simulation using transfer matrix method by varying the thickness of ZnO seed layer and thin absorber layer. By employing appropriate device architecture, polymer solar cells fabricated using this UTMF-based electrode show efficiency as high as 9.49%, which is slightly higher compared to that of ITO-based device. From good agreement between the external quantum efficiency and optical modeling, it was found that the optimized microcavity configuration formed in UTMF-based device can greatly enhance the absorbance of the BHJ layer at longer wavelength as well as the favored exciton distribution for better charge transport and collection.     

Performance improvement of MEH-PPV:PCBM solar cells using bathocuproine and bathophenanthroline as the buffer layers

In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance (Rs), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.     

硅基有机太阳能电池光学性能分析

采用传输矩阵法的光学模型以及MATLAB软件模拟了硅基有机太阳能电池对入射光的吸收率和各层厚度的关系。模拟表明活性层对入射光的吸收率主要受其自身厚度影响,且由于微腔效应,这种结构的电池可以很大程度上优化活性层厚度;另外通过调节折射率匹配层厚度和传输层厚度也可以优化活性层对入射光的吸收率。在本文所讨论的厚度中,最佳传输层厚度为10 nm左右,最佳匹配层厚度为30 nm ZnS或者60 nm Alq₃。     

基底温度对喷涂技术制备大面积有机太阳能电池性能的影响

以聚3-己基噻吩（P3HT）和富勒烯衍生物（PCBM）体系的有机太阳能电池器件为基础,采用喷涂法制备了有机太阳能电池的空穴传输层和有机功能层,研究了基底温度对薄膜的形貌和器件性能的影响,并采用喷涂技术制备了一面积为11.2 cm²的大面积有机太阳能电池器件。研究发现,随着基底温度的升高,薄膜的粗糙度下降,吸收率提高,当基底温度为130 ℃时器件的性能最优,面积为25 mm²的器件的能量转换效率为2.09%。将多个独立的小面积电池进行串联和并联,制备了有效面积为11.2 cm²的大面积有机太阳能电池组件,其能量转换效率为1.83%,在面积增大44.8倍的情况下,效率仅损失不到13%。     

Bathocuproine/Ag复合电极对于聚合物光伏器件效率和稳定性的影响

采用Bathocuproine/Ag (BCP/Ag)复合电极代替Ca/Al复合电极, 制备PTB7:PC71BM 作为光敏层的聚合物光伏器件, 并通过改变BCP薄膜厚度来研究BCP/Ag复合电极对于器件光电转换器和稳定性的影响. 研究发现: 在光敏层和金属电极之间插入BCP修饰层后, 器件性能得到了显著的改善, 在BCP厚度为5 nm时, 器件的效率达到了6.82%, 且略高于Ca/Al复合电极的器件效率; 相比于采用Ca/Al复合电极的器件, BCP/Ag复合电极增大了器件的短路电流和外量子效率, 使器件效率得到提高; 同时器件的稳定性得到了显著的改善, BCP/Ag 复合电极器件的衰减速率几乎和未插入BCP的器件衰减速率相同, 相对于Ca/Al复合电极器件大幅提高.     

Improved performance of polymer solar cells by using inorganic,organic, and doped cathode buffer layers

The interface between the active layer and the electrode is one of the most critical factors that could affect the device performance of polymer solar cells. In this work, based on the typical poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester(P3HT:PCBM) polymer solar cell, we studied the effect of the cathode buffer layer(CBL) between the top metal electrode and the active layer on the device performance. Several inorganic and organic materials commonly used as the electron injection layer in an organic light-emitting diode(OLED) were employed as the CBL in the P3HT:PCBM polymer solar cells. Our results demonstrate that the inorganic and organic materials like Cs_2CO_3, bathophenanthroline(Bphen), and 8-hydroxyquinolatolithium(Liq) can be used as CBL to efficiently improve the device performance of the P3HT:PCBM polymer solar cells. The P3HT:PCBM devices employed various CBLs possess power conversion efficiencies(PCEs) of 3.0%–3.3%, which are ca. 50% improved compared to that of the device without CBL. Furthermore, by using the doped organic materials Bphen:Cs_2CO_3 and Bphen:Liq as the CBL, the PCE of the P3HT:PCBM device will be further improved to 3.5%, which is ca. 70% higher than that of the device without a CBL and ca. 10% increased compared with that of the devices with a neat inorganic or organic CBL.     

The effect of post-annealing on the interface between the aluminum electrode and the active layer in polymer/fullerene solar cells

The post-annealing effects on the performance of poly (3-hexylthiophene) (P3HT)/(6,6)-phenyl C₆₁ butyric acid methyl ester (PCBM) solar cells with conventional bulk heterojunction (CBHJ) and layer-evolved bulk heterojunction (LBHJ) have been compared. It is found that contrary to the much better performance obtained from CBHJ cells, the post-annealing deteriorates the performance of LBHJ devices. Aqueous contact angle and X-ray photoelectron spectroscopy measurements show that P3HT is dominant at the top surface of CBHJ film, while PCBM is dominant at the top surface of LBHJ film. The micron-scale morphology evolution of the active layer/Al interface upon post-annealing reveals that the PCBM-rich surface is beneficial for the nucleation and growth of PCBM crystal, which does harm to the contact between the active layer and the electrode and results in the decrease of the fill factor. However, the original P3HT-rich surface prevents the formation of large surface-segregated PCBM clusters upon post-annealing, which is highly desirable for the efficient polymer/fullerene solar cells.