有机光伏器件—高效聚合物太阳电池和近红外光电探测器

发布时间：2018-09-01 07:25

【摘要】：有机光伏器件由于其具有轻便、低成本以及可以溶液加工等优点而受到广泛关注。然而，可用于溶液加工的有机光伏器件—聚合物太阳电池以及聚合物近红外光电探测器在能量转换效率以及器件稳定性等方面，与传统的无机光伏电器件相比还处于劣势。鉴于此，本论文的主要工作就是基于可溶液加工的聚合物材料体系,对光伏器件制备工艺进行优化设计，提高聚合物太阳电池以及近红外光电探测器的性能，探索实现溶液加工工艺制备高性能的聚合物光伏器件的新途径。我们首先研究了基于萘[1,2-c:5,6-c]二[1,2,5]噻二唑（萘二并噻二唑）的吸电子基团的“电子给体-电子受体”（donor-acceptor，D-A）型共轭聚合物(PBDT-DTNT)作为给体材料的太阳电池性能。由于萘二并噻二唑的强吸电子能力，聚合物PBDT-DTNT表现出优异的光电性能。我们主要从薄膜的纳米尺寸形貌对基于该聚合物的太阳电池性能进行优化研究，我们发现，热退火处理、溶剂添加剂等处理方法，能够提高基于该聚合物的太阳电池的性能，获得较高的能量转化效率，我们的研究和发现表明PBDT-DTNT是一种非常有潜力的电子给体材料。同时，我们的研究结果对于优化基于萘二并噻二唑的吸电子基团的一系列共轭聚合物作为给体材料的太阳电池器件有着重要的参考作用。在以上的研究基础之上，我们仍然采用PBDT-DTNT:PC71BM材料体系作为活性层材料，并采用可交联共轭聚合物PFN-OX作为电子抽取层，制备倒装聚合物太阳电池，系统研究了活性层薄膜的厚度与聚合物太阳电池性能的关系。通过湿法成膜，我们制备出一系列具有不同活性层厚度的的器件，厚度范围从85nm到1300nm。当活性层厚度为280nm时，得到最高的能量转换效率8.62%，当厚度在1000nm左右时，器件的能量转化效率仍有7.24%。我们发现，随着活性层厚度的增加，载流子的迁移率仍然保持较高的水平。通过掠入射小角X射线散射（GISAXS）以及掠入射广角X射线散射(GIWAXS)对不同厚度的活性层薄膜微观结构进行分析得出，厚度的增加并没有改变共混体系中聚合物链的高度有序性，意味着膜厚的增加并没有影响空穴在聚合物主链之间沿着聚合物骨架的传输，这是基于该材料体系的聚合物太阳电池在如此厚膜的情况下还能保持高效率的原因所在。我们的结果表明该材料体系在卷对卷（R2R，roll to roll）生产工艺上有非常大的应用潜力。第三部分工作中，我们基于一种新型的窄带隙共轭聚合物PTZBTTT-BDT，制备出了高性能的聚合物近红外光电探测器。鉴于水醇溶的共轭聚合物PFN能够提高聚合物太阳电池的各项性能，特别是能够降低器件的暗电流，我们将PFN应用于该聚合物近红外光电探测器的阴极修饰，在室温工作条件下，该探测器的光谱响应范围能够从紫外区域延伸至近红外区域（400nm-1100nm）。在400nm到950nm范围内，探测率高达1013cm.Hz1/2/W，在950nm到1100nm范围内，探测率高于1010cm.Hz1/2/W。我们发现，，加有PFN阴极修饰层的光电探测器展现出更好的二极管特性，在反向偏压下，器件的暗电流得到了很好的抑制，从而降低了因暗电流带来的噪声，因此使得加有PFN阴极修饰层的光电探测器展现出与无机硅探测器可比拟的优异性能。基于以上的研究工作，我们仍然采用以上近红外材料PTZBTTT-BDT作为活性层的给体材料，并采用可交联共轭聚合物PFN-OX作为电子抽取层，来制备倒装聚合物近红外光电探测器，同时采用传统的阴极修饰材料ZnO作为电子抽取层制备探测器进行对比研究。我们发现，在室温零偏压下，基于PFN-OX电子抽取层的光电探测器对800nm波长的近红外光的光响应率可达116mA/W，相应的探测率达到1.02×1013cm Hz1/2/W。而采用传统的电子抽取层ZnO的倒装探测器的探测率则为1.71×1012cm Hz1/2/W，比基于PFN-OX电子抽取层的光电探测器的探测率几乎小一个数量级，这一结果证明，PFN-OX薄膜相比ZnO薄膜具有更好的阴极修饰作用。同时，我们的实验结果表明，采用PFN-OX修饰ITO阴极制备倒装聚合物光电探测器，是获得高性能的倒装聚合物光电探测器的一条十分有效的途径。
[Abstract]:Organic photovoltaic devices have attracted much attention due to their advantages such as light weight, low cost and solution processing. However, polymer solar cells and polymer near-infrared photodetectors, which can be used for solution processing, are more efficient in energy conversion and device stability than traditional inorganic photovoltaic devices. In view of this, the main work of this paper is to optimize the preparation process of photovoltaic devices, improve the performance of polymer solar cells and near-infrared photodetectors, and explore new ways to fabricate high-performance polymer photovoltaic devices by solution processing technology. Way.
We first investigated the properties of the donor-acceptor (D-A) conjugated polymer (PBDT-DTNT) based on the electron-absorbing group of naphthalene [1,2-c:5,6-c] bis [1,2,5] thiadiazole (NBDT). The polymer PBDT-DTNT exhibited excellent performance as a donor material for solar cells due to its strong electron-absorbing ability. Different photoelectric properties. We mainly optimize the performance of solar cells based on the polymer film from the nano-size morphology. We found that the thermal annealing treatment, solvent additives and other treatment methods can improve the performance of solar cells based on the polymer and obtain higher energy conversion efficiency. Ming PBDT-DTNT is a promising electron donor material, and our results have important reference value for optimizing a series of conjugated polymers based on the electron-absorbing groups of naphthalene dithiadiazole as donor materials for solar cell devices.
On the basis of the above research, we still use PBDT-DTNT:PC71BM material system as active layer material and cross-linked conjugated polymer PFN-OX as electron extraction layer to prepare flip-chip polymer solar cells. The relationship between the thickness of active layer film and the performance of polymer solar cells is studied systematically. A series of devices with different active layer thicknesses were fabricated, and the thickness ranged from 85 nm to 1300 nm. When the active layer thickness was 280 nm, the highest energy conversion efficiency was 8.62%. When the thickness was about 1000 nm, the energy conversion efficiency was still 7.24%. We found that with the increase of the active layer thickness, the carrier mobility was still maintained. The results of grazing incidence small angle X-ray scattering (GISAXS) and grazing incidence wide angle X-ray scattering (GIWAXS) show that the increase of thickness does not change the high order of polymer chains in the blends, which means that the increase of film thickness does not affect the polymerization of holes in the blends. The transport of the main chains along the polymer skeleton is the reason why polymer solar cells based on this material system can maintain high efficiency even with such a thick film.
In the third part, based on a novel narrow band-gap conjugated polymer PTZBTTT-BDT, we fabricated polymer near-infrared photodetectors with high performance. Considering that water-soluble conjugated polymer PFN can improve the performance of polymer solar cells, especially reduce the dark current of the devices, we applied PFN to the polymerization. In the range of 400 nm to 950 nm, the detection rate is as high as 1013 cm.Hz 1/2/W. In the range of 950 nm to 1100 nm, the detection rate is higher than 1010 cm.Hz 1/2/W. We found that the negative PFN is added. Photodetectors with PFN coatings exhibit better diode characteristics. Under reverse bias, the dark current of the device is well suppressed, thus reducing the noise caused by dark current. Therefore, photodetectors with PFN coatings exhibit superior performance compared with inorganic silicon detectors.
Based on the above research work, we still use the above near infrared material PTZBTTT-BDT as the donor material of the active layer, and use the crosslinked conjugated polymer PFN-OX as the electron extraction layer to prepare flip-chip polymer near infrared photodetectors. At the same time, we use the traditional cathode modified material ZnO as the electron extraction layer to prepare the detector. It is found that the photodetector based on PFN-OX electron extraction layer has a response rate of 116 mA/W to near infrared light of 800 nm wavelength at room temperature and zero bias voltage, and the corresponding detection rate is 1.02 *1013 cm Hz 1/2/W. The flip-chip detector based on traditional electron extraction layer ZnO has a detection rate of 1.71 *1012 cm Hz 1/2/W, which is a ratio. The detectivity of the photodetectors based on the PFN-OX electron extraction layer is almost one order of magnitude smaller, which proves that the PFN-OX film has better cathodic modification effect than the ZnO film. At the same time, our experimental results show that the flip-chip photodetectors based on the PFN-OX modified ITO cathode are good flip-chip polymers. A very effective way of photodetectors.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM914.4;TN215

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