高性能本体异质结聚合物太阳能电池

HIGH PERFORMANCE BULK HETEROJUNCTION POLYMER SOLAR CELLS

闫政龙

11649153

硕士

材料工程

郭旭岗

2018-06-01

2018-07-02

哈尔滨工业大学

深圳

有机光伏（OPV）领域经过过去十年的不断发展，能量转换效率（PCE） 从 1%提升到了 15%。对于半导体聚合物而言，这些太阳能电池由溶液加工技术制备所得，并且其材料和制备条件的优势在未来具有很大发展前景。聚合物太阳能电池应用范围很广，从柔性太阳能电池和窗户上的半透明有机太阳能电池再到液晶显示器中的光子再循环。针对这些聚合物太阳能电池探索中，活性层材料设计与合成以及器件的制备与优化一直都是研究人员关注的焦点和研究聚合物太阳能电池的关键。本课题组通过在 3,3'-二烷氧基-2,2'-联噻吩（BTOR）单元中插入缺电子基 团氟代苯，开发了一种新型结构单元 1,4-二（3-烷氧基-2-噻吩基）-2,5-二氟亚苯基（DOTFP），这种结构单元具有较高共面性、理想的最高占据分子轨道（HOMO）能级、优异的溶解性。根据这种结构单元合成了三种基于 DOTFP和苯并噻二唑（BT）衍生物的 D-A1-D-A2 型聚合物，与基于 BTOR 单元 D-A型聚合物进行对比。实验制备了四种聚合物材料本体异质结聚合物太阳能电池，通过器件性能测试和形貌研究分析发现，基于 DOTFP-ffBT 的太阳能电池与基于 BTOR-ffBT 的太阳能电池相比表现出 8.7％的较高能量转换效率（PCE），其中 Voc 提升到 0.84 V，而 BTOR-ffBT 只有 2.6％的 PCE 和 0.49 V 的 Voc。基于DOTFP-ffBT 太阳能电池 8.7％的 PCE 和 0.84 V 的 Voc 值是所有含烷氧基噻吩聚合物中性能最高的。并且，跟基于 BTOR 单元聚合物相比，DOTFP 基聚合物表现出更好电荷传输性能和优异的共混膜形貌结构，同时在活性层中引入添加剂都有效调节了活性层形貌提升了这几种聚合物的光伏性能。这些结果表明DOTFP 是用于构建具有较大 Voc 高性能光伏聚合物半导体的潜力单元。迄今为止，在全聚合物太阳能电池领域的各种 n 型有机半导体材料中，基于萘二酰亚胺（NDI）和苝二酰亚胺（PDI）为构建单元的聚合物一直都是研究热点。尤其，目前 PCE > 5％的全聚合物太阳能电池 n 型受体材料几乎完全基于 NDI 和 PDI 部分构建。因此，我们需要开发出一类全新结构的 n 型聚合物半导体来进一步优化提升全聚合物太阳能电池的性能。所以，本课题组最近还设计合成了基于双噻吩酰亚胺（BTI）单元的 n 型聚合物半导体，通过单键连接BTI 单元的 s-BTI2-FT 和稠环 f-BTI2-FT 以及更多 BTI 单元稠环聚合物半导体材料。基于稠环化的 f-BTI2-FT 表现出比基于单键相连的二聚体 s-BTI2-FT 更小光 学带隙和更高的结晶性。当与 p 型聚合物 PTB7-TH 共混后所制备的全聚合物太阳能电池达到 6.85%的能量转换效率。这是除了基于萘（或苝）二酰亚胺聚合物受体材料全聚合物太阳能电池以外较高值。然而，s-BTI2-FT 器件几乎没有光伏性能。结果表明，BTI 单元的稠环化是提高聚合物电性能的有效途径。随后，通过稠环作用引入了更多 BTI 单元，这些不同 BTI 单元数量的聚合物材料f-BTI(1-4)-FT 光学性质表现出显著差异，在与 PTB7-TH 混合后制备活性层薄膜也呈现出不同程度相分离结构。这四个聚合物材料中，基于 f-BTI3-FT 为受体材料本体异质结全聚合物太阳能电池能量转换效率达到最高 7.34%，这也是迄今为止全聚合物太阳能电池领域中除 NDI 和 PDI 受体材料以外电池性能最高之一。

Organic photovoltaic (OPV) technology has risen from 1% to 15%, especially by going decades of continuous energy conversion efficiency (PCE). Based on sem_x005ficonducting polymers, these solar cells are fabricated from solution-processing techniques and have unique prospects for achieving low-cost solar energy harvesting, owing to their material and manufacturing advantages. The potential applications of polymer solar cells are broad, ranging from flexible solar modules and semitransparent solar cells in windows, to building applications and even photon recycling in liquid-crystal displays. The design and synthesis of these polymer solar cell active layer materials, as well as the device preparation and optimization has always been the focus of researchers, and is also the key to the study of polymer solar cells.A new building block, 1,4-di(3-alkoxy-2-thienyl)-2,5-difluorophenylene(DOTFP) with several desirable features such as high backbone planarity, suitably lying highest occupied molecular orbital (HOMO), and good solubility, was developed by inserting an electron-deficient difluorophenylene into the 3,3′-dialkoxy-2,2′-bithiophene (BTOR) unit. Three regioregular D-A1-D-A2 type polymers based on DOTFP and benzothiadiazole (BT) derivatives were synthesized and characterized by comparing with a D-A type BTOR-based polymer. Then,polymer solar cell were fabricated through experiments. As a result, the DOTFP-ffBT based solar cells exhibited a significantly improved power conversion efficiency (PCE) of 8.7% with dramatically enlarged Voc of 0.84 V, when compared to BTOR-ffBT based solar cells which show a PCE of 2.6% and Voc of 0.49 V. The PCE of 8.7% and the Voc of 0.84 V for DOTFP-ffBT based solar cells are one of the highest values among all mainchain-containing alkoxythiophene based polymers.What’s more, DOTFP-based polymers exhibited improved charge transport properties and better film morphology than BTOR-based polymer. At the same time, the introduction of additives in the active layer effectively regulates the morphology of the active layer and enhances the photovoltaic performance of these polymers. These results indicate that DOTFP is a potential unit for the construction of high performance photovoltaic polymer semiconductors with large Voc.Among various n-type organic semiconductors developed to date, polymers based on naphthalene diimide (NDI) and perylene diimide (PDI) show the most promising performance in all-PSCs. Indeed, n-type polymer acceptors showing PCE > 5% are almost exclusively built on the basis of NDI and PDI moieties.Therefore, the development ofother kinds of n-type polymers is required to establish structure-roperty relationships and further optimize all-PSC performance. Two new bithiophene imide (BTI)-based n-type polymers were synthesized by our group. f-BTI2-FT based on a fused BTI dimer showed a smaller band gap, a lower LUMO, and higher crystallinity than s-BTI2-FT containing a BTI dimer connected through a single bond. When blended with the polymer donor PTB7-Th, f-BTI2-FT based all-polymer solar cells (all-PSCs) attained a PCE of 6.85%, the higher value for an all-PSC not based on naphthalene (or perylene) diimide polymer acceptors. However, s-BTI2-FTall-PSCs showed nearly no photovoltaic effect. The results demonstrate that f-BTI2-FT is one of most promising n-type polymers and that ring fusion offers an effective approach for designing polymers with improved electrical properties.Subsequently, more BTI units were introduced through the fused ring. These different numbers of BTI units caused changes in the energy level of the polymer material, movement of the absorption curve, and different degrees of phase separation of the active layer. When blended with the polymer donor PTB7-Th , f-BTI(1-4)-FT based all-polymer solar cells (all-PSCs) exhibited different photovoltaic properties.Among them, the f-BTI3-FT based bulk heterojunction all-polymer solar cell reached the highest energy conversion efficiency of 7.34%, which is the highest performance all-polymer solar cell except the NDI and PDI receptor materials so far.

有机光伏 烷氧基 双噻吩 酰亚胺 稠环 二聚体

Organic photovoltaic alkoxy bithiophene imide ring fusion dimer

中文

联合培养

南方科技大学

闫政龙. 高性能本体异质结聚合物太阳能电池[D]. 深圳. 哈尔滨工业大学,2018.