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首页> 外文学位 >Interface and charge transport studies in organic solar cells based on P3HT:PCBM bulk heterojunctions.
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Interface and charge transport studies in organic solar cells based on P3HT:PCBM bulk heterojunctions.

机译：基于P3HT：PCBM本体异质结的有机太阳能电池的界面和电荷传输研究。

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摘要

Interfaces and charge transport in organic solar cells based on P3HT:PCBM bulk heterojunctions (BHJ) were studied. State-of-the-art TEM sample preparation techniques, including in-situ lift-out, were used with a dual focused ion beam (FIB) system on a typical device (ITO/PEDOT:PSS/P3HT:PCBM/Al). Through bright field (BF) TEM micrographs a mixed layer between the Al electrode and the organic active layer (P3HT:PCBM) was clearly observed in both as-fabricated and annealed devices. The effect of Al contact resistance before and after annealing was studied using the vertical transmission line model (TLM). It was found that by annealing after Al evaporation, the contact resistivity decreased by 38%.;Energy filtered transmission electron microscopy (EFTEM) clearly revealed a nanoscopic phase separation. From the EFTEM images, the average length and the diameter of P3HT fibrils were found to be approximately 70 nm and 15 nm, respectively. Combining the EFTEM, selected area electron diffraction (SAED) patterns and X-ray diffraction (XRD) results, the number and spacing of the ordered polymer chains in P3HT fibrils were calculated. There were about 18 repeating units of P3HT perpendicular to the fibril, about 184 layers of pi-pi* stacking along the fibril and about 9 layers of interchain stacking within the fibril. Accompanied by cross-section samples prepared by the FIB technique, the vertical morphology of each phase was analyzed. By collecting 30 eV energy loss images, the phase separation in the blend of P3HT:PCBM was distinguishable. A higher P3HT concentration was observed at the top of the cell.;The temperature dependent charge separation and charge transport were studied using modulated surface photovoltage spectroscopy (SPV) on layers of P3HT, PCBM, and the blend. The unchanged character of the SPV spectra on the P3HT provides evidence that the mechanisms of charge separation, recombination and charge transport does not change qualitatively after cooling. It was important to point out that the SPV onset of the blend (P3HT:PCBM) occurred at a photon energy of about 1.0 eV, which was not in the range of reported optical band gap of either P3HT or PCBM. These SPV signals were assigned to charge separation from charge transfer (CT) states laying within the band gap of P3HT.
机译：研究了基于P3HT：PCBM本体异质结（BHJ）的有机太阳能电池的界面和电荷传输。在典型设备（ITO / PEDOT：PSS / P3HT：PCBM / Al）上，采用双聚焦离子束（FIB）系统使用最先进的TEM样品制备技术，包括原位提样。通过明场（BF）TEM显微照片，可以在预制和退火设备中清楚地观察到Al电极和有机活性层之间的混合层（P3HT：PCBM）。使用垂直传输线模型（TLM）研究了退火前后铝接触电阻的影响。通过铝蒸发后的退火发现，接触电阻降低了38％。能量过滤透射电子显微镜（EFTEM）清楚地显示出纳米相分离。从EFTEM图像中，发现P3HT原纤维的平均长度和直径分别为约70nm和15nm。结合EFTEM，选择区域电子衍射（SAED）模式和X射线衍射（XRD）结果，计算了P3HT原纤维中有序聚合物链的数量和间距。垂直于原纤维存在约18个重复的P3HT重复单元，沿原纤维堆叠约184层pi-pi *，在原纤维内部堆叠约9层链间。结合通过FIB技术制备的横截面样品，分析了每个相的垂直形态。通过收集30 eV能量损失图像，可以区分P3HT：PCBM混合物中的相分离。在电池顶部观察到更高的P3HT浓度。;使用调制表面光电压谱（SPV）在P3HT，PCBM和共混物上研究了温度依赖性电荷分离和电荷传输。 P3HT上SPV光谱的不变特征提供了证据，表明冷却后电荷分离，重组和电荷传输的机制不会发生质变。重要的是要指出，共混物（P3HT：PCBM）的SPV发生在大约1.0 eV的光子能量下发生，这不在P3HT或PCBM的报告光带隙范围内。将这些SPV信号分配给与位于P3HT的带隙内的电荷转移（CT）状态分离的电荷。

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  • 作者

    Rujisamphan, Nopporn.;

  • 作者单位

    University of Delaware.;

  • 授予单位 University of Delaware.;
  • 学科 Engineering Materials Science.;Chemistry Polymer.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 105 p.
  • 总页数 105
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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