热处理对不同溶剂制备的共混体系太阳电池性能影响

本文以poly(3-hexylthiophene) (P3HT)为电子给体材料, -phenyl C₆₁-butyric acid methyl ester (PCBM)为电子受体材料, 制备出不同溶剂形成的共混体系太阳电池.从薄膜的紫外—可见吸收光谱(UV-vis)、光致发光谱(PL)、原子力表面图形(AFM)等方面,分析了热处理对不同溶剂制备的共混体系太阳电池性能的影响.结果表明较高沸点的溶剂有利于P3HT:PCBM共混体系中P3HT的有序化排列,薄膜的紫外—可见吸收和光致发光增 关键词： 热处理 不同溶剂 太阳电池 性能     

基于P3HT给体的单/双受体平面异质结电池性能及其介电特性

为了研究分析界面电荷等特性对器件的影响,制备了基于P3HT给体的单/双受体平面异质结(PHJ)有机太阳能电池(OPV)。首先研究了P3HT膜厚、P3HT溶剂和P3HT膜层的干燥时间对器件性能的影响。为了提高P3HT/Sub Pc PHJ电池的性能,采用双受体的三元器件结构(P3HT/Sub Nc/Sub Pc),制备了结构为ITO/PEDOT∶PSS/P3HT/Sub Nc/Sub Pc/BCP/Al的三元瀑布型OPV器件并研究了Sub Nc层厚度对其性能的影响。结果表明,在二元器件(P3HT/Sub Pc)体系中,P3HT溶于氯仿和1,2-二氯苯混合溶剂,成膜后干燥10 min退火获得的器件性能最佳。在三元器件中,随着Sub Nc厚度的增大,器件光电转换效率(PCE)先增大后减小。当Sub Nc厚度为5 nm时,器件PCE达到最大。相比于二元器件,三元器件的各项性能得到明显提升。最后,比较研究了不同厚度Sub Nc薄膜对器件介电特性的影响。     

CdSe量子点掺杂聚合物太阳能电池光谱响应特性研究

采用喷涂法分别制备了基于P3HT∶PCBM体异质结和P3HT∶PCBM∶QDs体异质结光活性层的有机太阳能电池器件,并对其光电响应进行了表征和对比。同时采用光谱手段对两者的光活性层进行对比分析。实验结果表明,量子点的加入拓宽了薄膜吸收光谱,同时增强了光致电子转移过程,从而改善了器件的光谱响应;双源共喷制备的P3HT∶PCBM∶QDs体异质结器件转化效率比同样是喷涂制备的P3HT∶PCBM体异质结提高了25%。     

磁场对P3HT:PCBM活性层的薄膜形貌及光电性能的影响

以P3HT(Poly(3-Hexylthiophene))为电子给体,PCBM([6,6]-Phenyl C61Butyric Acid Methyl Ester)为电子受体,在活性层P3HT:PCBM的退火过程中,利用磁场对活性层有机分子的排列取向作用,制备了有机体异质结太阳能电池。研究结果表明:当磁场强度为0.9MA/m时,器件的短路电流密度从7.414A/cm2提高到8.332A/cm2,填充因子也相应地增加,但开路电压却有所降低,最高的光电转换效率为2.562%。由光致发光光谱和原子力显微图像可知,磁场对活性层的结晶度、内部分子排列和表面形貌都有明显的影响。     

NPB阳极缓冲层对反型结构聚合物太阳能电池性能的影响

制备了给体材料为poly(3-hexylthiophene)(P3HT),受体材料为[6,6]-phenyl-C60-butyric acid methyl ester(PCBM),器件结构为ITO/ZnO/P3HT:PCBM/NPB(0,1,5,10,25 nm)/Ag的反型体异质结聚合物太阳能电池.不同厚度的N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine(NPB)阳极缓冲层被用来改善器件性能,研究了NPB阳极缓冲层对器件特性的影响.研究发现,1 nm厚的NPB改善了器件的载流子收集效率,增加了器件的短路电流与开路电压.当NPB缓冲层的厚度达到25 nm时,过厚的NPB导致串联电阻增加,使得器件特性大幅下降.通过电容-电压测试,进一步研究了不同厚度NPB对器件载流子注入与收集的影响,1 nm厚的NPB修饰并没有改善器件的载流子注入但是增加了器件对光生载流子的收集效率,过厚的NPB使得自由载流子的复合占据主导.适合厚度的NPB可以作为一种阳极缓冲层材料应用于聚合物太阳能电池提高器件特性.     

溶剂预处理结合热退火提升聚噻吩结晶度及其光伏性能

活性层的微观形貌在很大程度上决定了聚合物光伏器件的性能表现并依赖于制备工艺条件。为了改善薄膜内部分子排布结构并追求较高的器件光电转化效率,采用溶液法制备了基于P3HT∶PCBM的聚合物太阳能电池(器件结构:ITO/PEDOT∶PSS/P3HT∶PCBM/Al),通过改变器件制备流程中活性层退火处理工艺,研究了热退火、溶剂退火以及溶剂预处理结合热处理的双重退火对聚合物太阳电池性能的影响。研究发现:双重退火的光伏器件的各项性能参数均优于单一退火处理器件,获得了3.25%的光电转化效率。原子力显微镜及X射线衍射仪的表征结果进一步证明:双重退火处理能够在促进聚合物给体良好有序结晶的同时保证共混组分适度地相分离,从而有利于光生激子的解离以及载流子的传输。     

二甲基亚砜添加剂对聚合物太阳能电池性能的影响

研究了二甲基亚砜(DMSO)掺杂浓度对基于聚(3-己基噻吩)(P3HT)和(6,6)-苯基碳60丁酸甲酯(PCBM)为有源层的聚合物太阳能电池性能影响。结果表明,掺杂DMSO可以提高聚合物太阳能电池短路电流密度和填充因子。DMSO掺杂质量比为3%时,电池短路电流密度提高到7.88 mA·cm-2,填充因子为55.5%。能量转换效率达到2.54％,相比没有掺杂DMSO的电池,能量转换效率提高了17%。傅里叶变换红外光谱被用于鉴定和分析掺杂DMSO对材料P3HT∶PCBM化学性质的影响。傅里叶变换红外光谱表明,掺杂后P3HT和PCBM的化学性质都没有改变。为分析掺杂DMSO改善器件能量转换效率的原因,通过紫外-可见光谱和电流密度-电压特性曲线分别表征器件的光吸收能力以及电致发光器件的载流子迁移率。与P3HT∶PCBM薄膜相比,P3HT∶PCBM∶DMSO薄膜在可见光范围内的吸收峰有明显红移且吸收强度增强。可见光吸收的改善是实现短路电流密度提高的有力保障。太阳能电池性能的增强是因为DMSO的掺杂提高了P3HT∶PCBM的载流子迁移率和吸收光谱宽度。     

不同环境压强下溶剂退火对聚合物太阳能电池性能的影响

通过改变溶剂退火时的环境压强控制溶剂的蒸发速率,在不同压强下进行加压溶剂退火制备了基于聚-3己基噻吩:富勒烯衍生物(P3HT:PCBM)的体异质结聚合物太阳能电池。X射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)以及原子力显微镜(AFM)的测试结果表明,增大溶剂退火的环境气压改善了薄膜的结晶度,增强了有源层的光吸收,提高了P3HT和PCBM的相分离程度,更有利于激子的解离和载流子传输。与在常压下溶剂退火相比,在2.0 MPa压强下对有源层进行溶剂退火的器件的光电转换效率提高了29%,达到了3.69%。     

磁场对P3HT:PCBM活性层的薄膜形貌及光电性能的影响北大核心CSCD

以P3HT(Poly(3-Hexylthiophene))为电子给体,PCBM([6,6]-Phenyl C61Butyric Acid Methyl Ester)为电子受体,在活性层P3HT:PCBM的退火过程中,利用磁场对活性层有机分子的排列取向作用,制备了有机体异质结太阳能电池。研究结果表明:当磁场强度为0.9MA/m时,器件的短路电流密度从7.414A/cm2提高到8.332A/cm2,填充因子也相应地增加,但开路电压却有所降低,最高的光电转换效率为2.562%。由光致发光光谱和原子力显微图像可知,磁场对活性层的结晶度、内部分子排列和表面形貌都有明显的影响。     

基于卟啉化合物的异质结有机太阳能电池

采用混合溶剂制备了四苯基卟啉(TPP)及其铜配合物(TPPCu)和氯化对甲氧基四苯基铁卟啉(TMPPFeCl),将三种卟啉化合物和富勒烯的衍生物(PCBM)分别共混,制备异质结太阳能电池。器件结构是ITO/porphyrin∶PCBM/Al,研究此类电池的性能。结果显示基于TPP∶PCBM的器件性能最优,其短路电流密度(JSC)是0.98mA.cm-2,开路电压(VOC)是0.52V,填充因子(FF)为30.1%。TPP是三种卟啉化合物中最佳的给体材料。进而考察了TPP∶PCBM的不同浓度配比对器件性能的影响。TPP∶PCBM的最佳浓度配比为1∶1,增加或减少TPP的量都会使器件的短路电流和开路电压降低,对填充因子的影响不大。     

Effect of solvents on the performance and morphology of polymer photovoltaic devices

In the polymer photovoltaic devices (PVDs), the performance of devices was strongly influenced by region-regularity, number average molecular weight and casting solvents of polymers. In this work, we fabricated p–n bulk-hetero-junction PVDs based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₀-butyric acid methyl ester (PCBM) using various solvents such as chloroform (CF), chlorobenzene (CB), dichlorobenzene (DCB), and mixed solvent (CF/CB, CF/DCB). Thin film of active layer with P3HT/PCBM was prepared by spin coating and thermal annealing at 150 °C with fixed thickness about 110 nm by adjusting solution concentration. The crystalline morphology and layered phase for the active layer were studied by atomic force microscopy and X-ray diffraction, respectively. We investigated the performance of solar cells according to different morphology and crystallinity of active layer by various solvent and mixed solvent.     

Influence of morphology of PCDTBT:PC71BM on the performance of solar cells

Because of the restriction of low energy difference between the highest occupied molecular orbital of P3HT and the lowest unoccupied molecular orbital of PCBM, the obtained power conversion efficiency of P3HT:PCBM solar cells is merely half the ideal value. In this paper, we have fabricated bulk heterojunction solar cells based on PCDTBT and PC71BM (structure: ITO/PEDOT:PSS/PCDTBT:PC71BM/LiF (0.8 nm)/Al (80 nm)). In order to optimize the performance of the cells, the weight ratio of PCDTBT to PC71BM, the thickness of the active layer and thermal annealing are investigated. When the weight ratio of PCDTBT to PC71BM is 1:2 and the thickness of the active layer is 73 nm, a short circuit current density of 10.36 mA/cm², an open-circuit voltage of 0.91 V, a fill factor of 55.06 % and a power conversion efficiency of 5.19 % can be achieved. Moreover, we probe the influence of annealing temperature on the performance of organic solar cells, and find that the thermal treatment methodology (apart from the removal of trapped casting solvent) is of limited benefit.     

Preheated solvent exposure on P3HT:PCBM thin film: A facile strategy to enhance performance in bulk heterojunction photovoltaic cells

In this study, we explored the ability of a preheated solvent (methanol) to induce characteristic changes at the organic active layer/metal interface, thereby improving the performance of fabricated organic photovoltaic (OPV) cells composed of poly(3-hexylthiopene) (P3HT) and a [6,6]-phenyl-C₇₁-butyric acid methyl ester (PCBM) photoactive blend. Our results demonstrate that exposure to methanol (at room temperature, or preheated at 45 °C or 65 °C) improves the performance of the fabricated OPV cells. After preheated methanol exposure, the P3HT:PCBM thin films were tested for crystallinity, morphology, mobility, and photovoltaic characteristics. Our results revealed that use of the preheated solvent on the organic active layer significantly influences the micro/nano scale morphology and phase segregation of the P3HT:PCBM thin films, as well as the charge carrier mobility. It is hypothesized that the side chain ordering of P3HT and redistribution of PCBM could be results of the modified active layer. Consequently, OPV cells modified with the methanol preheated at 65 °C exhibited a power conversion efficiency (PCE) of 3.36%, with open-circuit voltage of 0.59 V, short-circuit current density of 13.83 mA/cm², and fill-factor of 0.41. In contrast, the unmodified P3HT:PCBM thin film (without methanol exposure) showed a PCE of only 2.13%.     

The inverted solar cells with the polymer:fullerene blend film possessing a stratified composition profile

The inverted polymer:fullerene solar cells with structure of ITO/TiO₂/P3HT:PCBM/MoO₃/Al have been fabricated, where P3HT and PCBM stand for poly (3-hexylthiophene) and [6,6]-phenyl C₆₁-butyric acid methyl ester, respectively. It is discovered that the P3HT:PCBM blend film manipulated into the improved stratification structure, characterized as P3HT crystallite-rich zone close to the top surface and PCBM constituent-rich zone adjacent to the bottom surface, can offer nearly the same power conversion efficiency of solar cell, compared to the one grown into the bulk heterojunction structure, characterized as the bicontinuous interpenetrating network of P3HT and PCBM. We provide an alternative insight to the morphology control of inverted polymer:fullerene solar cells.     

Mechanisms controlling the efficiency of polymer solar cells

To improve the efficiency of polymer solar cells, it is vital to understand which mechanisms control the current–voltage characteristics of a given device. Temperature and light intensity dependence of the main solar cell parameters are very informative for analyzing losses. We report on the current–voltage characteristics and the external photogeneration quantum yield of ITO/PEDOT:PSS/OC1C10-PPV:PCBM/Al as well as of ITO/PEDOT:PSS/P3HT:PCBM/Al devices investigated in the broad temperature range 120–325 K under variable illumination, between 0.02 and 100 mW/cm². We discuss the recombination on traps and the low mobility of charge carriers caused by poor morphology of active layers as possible mechanisms limiting the efficiency of these devices. PACS 73.50.P; 73.61.P; 72.80.R     

Influence of fullerene derivative replacement with TiO2 nanoparticles in organic bulk heterojunction solar cells

In an effort to develop hybrid organic solar cells with improved power conversion efficiency (PCE), devices based on poly (3-hexylthiophene) (P3HT):phenyl C₆₁-butyric acid methyl ester (PCBM) active layer and poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrenesulfonate) (PSS) buffer layers were prepared. A systematic replacement of PCBM was achieved by introducing nanostructured TiO₂ (∼15 nm particle size), dissolved separately in chlorobenzene (CB) and 1,2 –dichlorobenzene (DCB), to the (P3HT:PCBM) active layer while keeping a fixed amount for P3HT. To understand the effect of fullerene replacement with the inorganic metal oxide nanoparticles on different properties of resulting devices, a variety of techniques such as Current–Voltage (J–V) characteristics, Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Ultravoilet-Visible (UV–Vis) Spectrophotometry and External Quantum Efficiency (EQE) were employed. The addition of TiO₂ nanoparticles in the active layer improved the power conversion efficiency (PCE) of P3HT:PCBM devices. The addition of TiO₂ nanoparticles using CB as solvent enhanced the absorption in visible region and also introduced a red shift in the absorption spectra. A significant increase in EQE was observed for devices with TiO₂ nanoparticles in the active layer. Mixing TiO₂ also increased the surface roughness of the active layer where TiO₂ nanoparticles were found to agglomerate as their concentration increased relative to fullerene derivative. A complete agglomeration of TiO₂ was observed in the absence of PCBM.     

Enhanced power efficiency of ZnO based organic/inorganic solar cells by surface modification

We present series of strategies to enhance efficiency of ZnO nanorods based organic/inorganic solar cells with spin-coated P3HT:PCBM blend as active layer. The performance of the as-fabricated devices is improved by controlling the size of ZnO nanorods, annealing temperature and time of active layer, surface modification of ZnO with PSBTBT. Optimized device of ITO/ZnO nanorod/P3HT:PCBM/Ag device with PSBTBT surface modification and air exposure reaches an efficiency of 2.02% with a short-circuit current density, open-circuit voltage and fill factor of 13.23 mA cm⁻², 0.547 V and 28%, respectively, under AM 1.5 irradiation of 100 mW m⁻², the increase in efficiency is 7-fold of the PSBTBT surface modified ITO/ZnO nanorods/P3HT:PCBM/Ag device compared with the unmodified one, which is own to the increased interface contact, expanded light absorption, tailored band alignment attributed to PSBTBT. We found exposure to air and surface modification is crucial to improve the device performance, and we discussed the mechanisms that affect the performance of the devices in detail.     

掺杂PEDOT ∶PSS对聚合物太阳能电池性能影响的研究

研究了掺杂后poly(3,4-ethylene dioxythiophene):poly(styrenesulphonic acid)(PEDOT ∶PSS)电导率的变化以及掺杂PEDOT ∶PSS薄膜对聚合物太阳能电池器件性能的影响. 实验发现,向PEDOT ∶PSS中掺入极性溶剂二甲基亚砜(DMSO)明显提高了薄膜的电导率,掺杂后的电导率最大值达到1.25 S/cm,比未掺杂时提高了3个数量级. 将掺杂的PEDOT ∶PSS薄膜作为缓冲层应用于聚合物电池 (ITO/PEDOT ∶PSS/P3HT ∶PCBM/LiF/Al) 中,发现高电导率的PEDOT ∶PSS降低了器件的串联电阻,增加了器件的短路电流,从而提高了器件的性能. 最好的聚合物太阳能电池在100 mW/cm²的光照下,开路电压(V_oc)为0.63 V,短路电流密度(J_sc)为11.09 mA·cm^-2,填充因子(FF)为63.7%,能量转换效率(η)达到4.45%. 关键词： PEDOT ∶PSS 电导率 聚合物太阳能电池 能量转换效率