聚合物太阳能电池阴极界面层及透明电极的研究

	聚合物太阳能电池阴极界面层及透明电极的研究
其他题名	Study on Cathode Interface Layer and Transparent Electrode of Polymer Photovoltaic Devices
	林逢源
学位类型	博士
导师	刘星元
	2015-11
学位授予单位	中国科学院大学
学位专业	凝聚态物理
关键词	聚合物太阳能电池阴极界面层透明电极功函数能量转换效率
摘要	能源危机在全球不断蔓延，人们迫切需要一种绿色环保、可持续再生的能源，取代日益消耗的化石资源。太阳能以其取之不尽用之不竭、获取方便、无污染的优点而备受人们瞩目。太阳能电池是可以将光能转化为电能最有效的途径，近年来发展势头正劲。其中，聚合物太阳能电池具有制备工艺简单、成本低、易实现柔性器件等优点，正逐渐吸引着大批研究者的目光。单层体异质结的聚合物太阳能电池效率也已经超过了10%。但是，如何继续提升器件的性能使其能够实用化，也是大家一直思考的问题，解决的方法主要有研制窄带隙给体材料提高活性层对光的吸收、改善活性层的表面形貌及相分离促进光生载流子的产生和输运、调整电极功函数使之与活性层材料能级匹配、改善电极/活性层界面、改良器件结构等。本论文针对以上部分方面开展工作，取得的主要研究成果如下：（1）选用多种金属氟化物用作聚合物太阳能电池的阴极界面层，其中，我们首次报道了用CeF3和SrF2作为阴极界面层的聚合物太阳能电池器件，SrF2阴极界面层的器件更是获得了7.17%的能量转换效率，比常用LiF器件高出9%。经过一系列研究对比，我们发现，器件性能与氟化物中对应金属的功函数（WFMIF）相关，随着WFMIF降低，器件的开路电压和填充因子按照AlF3< ZrF4< MgF2< LiF < CeF3< BaF2< SrF2的规律增加。经过紫外光电子能谱和X射线光电子能谱测试对金属氟化物/金属阴极进行电极有效功函数和成分的分析，证实了在金属氟化物/Al界面有置换反应发生和强偶极的存在，它们分别可以起到降低电极有效功函数和促进电荷收集的作用，因此可以将金属氟化物/金属阴极界面的作用机理归因于反应模式和偶极模式的双重作用。该工作也为今后研究金属氟化物在PSC器件中的作用机制、预估金属氟化物做阴极界面层的潜力和恰当地选择材料提供了一定的参考依据。（2）选用易溶于水的RbF材料作为倒置结构聚合物太阳能电池的阴极界面层，当RbF水溶液为3.0wt.‰时，聚合物太阳能电池器件获得了6.82%的能量转换效率，开路电压0.75V，短路电流15.19mA·cm-2，填充因子59.84%，串联电阻只有5.91Ω∙cm2。其能量转换效率是无阴极界面层器件的5倍，性能也比常用ZnO做阴极界面层的器件更优良。器件在某种程度上避免了PEDOT：PSS对电极及活性层材料的腐蚀，并且制备方法简单、环保无毒、成本低，也为开展全溶液太阳能电池器件的研制工作奠定了良好的基础。（3）用电子束热蒸发技术制备了基于多元氧化物（MoO3、WO3掺杂）的MWO/Ag/MWO薄膜。实现了在可见光区平均透过率达到75%，最高透过率为81%，方块电阻为6.8Ω·sq-1的，功函数为5.33eV的叠层透明导电薄膜，粗糙度只有0.506nm。以其为阳极制备的基于P3HT：PCBM活性层的聚合物太阳能电池器件不需要阳极界面层便得到了开路电压0.57V，短路电流8.43mA·cm-2，填充因子61.17%，最终获得2.94%的能量转化效率，是ITO为阳极的器件效率的2.18倍，比ITO/PEDOT:PSS器件的效率高出15%。
其他摘要	As the energy crisis in the world continues to spread, there is an urgent need for a green, renewable energy, to replace the growing consumption of fossil resources. Solar energy has attracted much attention for its advantages of inexhaustible, convenient acquisition and poisonless. In recent years, solar cells developed rapidly, which could convert light energy into electrical energy in the most effective way. Among them, the polymer solar cells (PSCs) are attracting researchers' eyes due to their advantages of simple preparation, low cost, and easy to realize flexible devices. The power conversion efficiency (PCE) of the single-layer bulk-heterojunction polymer solar cells has been reported to exceed 10%. However, to realize high PCE, the following factors are essential: a small-band gap donor to harvest the major fraction of solar photons, good morphology and phase separation of the active layer for efficient charge generation and transport, and electrodes with suitable work functions for formation of ohmic contacts and the maximum built-in electric field to facilitate charge extraction, improve the architecture of the device. This paper focuses on the cathode interfacial layers (CIL) and novel transparent electrode of PSCs, and the novel results are as following: (1) Different metal fluoride were used as cathode interface layer of PSC device, in which PSC devices with CeF3 and SrF2 as cathode interface layer were first reported. The SrF2 device obtained an excellent PCE of 7.17%, which was 9% higher than that of the typical LiF device.The performance of the device is related to the work function of the metal in the fluoride (WFMIF). The open-circuit voltage (VOC) and fill factor (FF) of the device were found to increase with the decrease of WFMIF in the following order: AlF3< ZrF4< MgF2< LiF < CeF3< BaF2< SrF2. Ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy measurements were performed to analyze the effective work function and composition of metal fluoride/metal cathode. It was confirmed that the mechanism operating at the fluoride/metal interface can be explained through a combination of the reaction and dipole models. This work will provide a useful reference for investigating the mechanism at the fluoride/metal interface in PSCs, estimating the effect of a metal fluoride CIL on PSC performance, and selection of interfacial layers to realize efficient PSCs in a simple way. (2) RbF cathode interface layers were prepared for the inverted polymer solar cells from aqueous solution. When the concentration of RbF aqueous solution is 3.0 wt.%, PSC device acquired a PCE of 6.82%, a VOC of 0.75 V, a short-circuit current density (JSC) of 15.19 mA∙cm-2, a FF of 59.84%, and a series resistance of 5.91 Ω∙cm2. The PCE is 5 times of the device without cathode interface layer, and the performance is even better than that of the typical ZnO based device. This method avoids the damage to the electrode in a certain extent and the active layer caused by the acidity of PEDOT:PSS. In short, this work proposes a simple processing, environmentally friendly and low cost CIL. (3) Transparent electrode MWO/Ag/MWO was prepared by electron beam evaporation technique. Average transmittance of 75% in the visible region, the highest transmittance of 81%, sheet resistance of 6.8 Ω∙sq-1, work function of 5.33eV and average RMS roughness of only 0.506nm were achieved. For the PSC device using MWO/Ag/MWO as anode and based on the active layer of P3HT:PCBM, a PCE of 2.94% was obtained, together with a VOC of 0.57V, a JSC of 8.43 mA∙cm-2, a FF of 61.17. Its PCE is 1.18 times higher than that of the device using ITO anode, and 15% higher than that of the device using ITO/PEDOT:PSS anode.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/49222
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	林逢源. 聚合物太阳能电池阴极界面层及透明电极的研究[D]. 中国科学院大学,2015.

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