【作者】 贺超；

【导师】 王坚；

【作者基本信息】 华南理工大学 ， 材料物理与化学， 2011， 博士

【摘要】 本论文的工作主要研究聚合物太阳电池的界面调控问题。在分析聚合物太阳电池电极修饰层的作用以及回顾聚合物太阳电池电极修饰材料研究进展的基础上,系统研究了不同的阴、阳极修饰层（共轭聚电解质,氧化钼MoO₃）对聚合物太阳电池性能尤其是开路电压的影响;系统分析了开路电压的影响因素,并提出了提高聚合物太阳电池开路电压的新的方法;在此基础上,将阴、阳极修饰层组成的中间电极成功地应用于叠层聚合物太阳电池,为聚合物太阳电池性能的进一步提高打下了坚实基础。共轭聚电解质被广泛地应用于聚合物电致发光器件（polymer light emitting diodes, PLED）,但其在聚合物太阳电池中的应用比较少见。我们将共轭聚电解质作为阴极修饰层,成功地应用于聚合物太阳电池。发现通过选择带合适的极性基团的共轭聚电解质,优化其厚度,能够有效地提高聚合物太阳电池的短路电流及填充因子,改善其性能。更重要的是,某些材料体系器件的开路电压（例如PFO-DBT35）由于共轭聚电解质层的引入得到了大幅提升。在分析共轭聚电解质层在聚合物太阳电池器件中的作用,并详细分析各组器件暗电流差别的基础上,我们用经典p-n结的肖克莱方程阐述了开路电压提高的原因。MoO₃是一个良好的阳极修饰层。文献中很多关于它对聚合物太阳电池短路电流、填充因子及整体性能的影响,却很少见到关于它对提高聚合物太阳电池器件开路电压的研究。MoO₃应用于P3HT、MEH-PPV、PFO-DBT35器件,发现对于具有更低HOMO能级的PFOD-BT35器件,其开路电压大幅提升。在综合分析其他一些实验结果的基础上,我们认为PFOD-BT35器件开路电压的提升并不是来自于阳极更好的欧姆接触,而可能是因为MoO₃的引入使得PFOD-BT35器件活性层中给体与受体在垂直方向上的产生了梯度分布,从而阴极处的PCBM有效的保护了活性层,防止了Al对PFOD-BT35的破坏而引起的能带弯曲。在上述阴、阳极修饰工作的基础上,提出了PFN/Al/MoO₃（PFN为一种共轭聚电解质）的三层结构中间电极,应用于叠层聚合物太阳电池。该中间电极加工相对简单,稳定性好,且具有良好的光、电学性能。通过选用窄带隙材料PBDT-DTNT器件作为上层子电池,得到了高达1.65V的开路电压,并成功使得叠层器件的效率超过了3%,填充因子超过了50%。我们认为,若选择更加合适的上层子电池给体材料,叠层聚合物太阳电池的效率将会有更大幅度的提升。更多还原

【Abstract】 The thesis focuses on interface engineering between active layer and electrodes for polymer solar cells （PSCs）. After a brief review of the interlayer materials and their functions, we carried a systematic study on the effects of interlayers from such as conjugated polyelectrolytes and MoO₃ on the performances of PSCs, especially on the open circuit voltage （Voc）. We successfully increased the Voc via electrode modification and analyzed the origin of its enhancement. In addition, we proposed a novel intermediate layer for polymer tandem solar cells with the structure of PFN/Al/MoO₃, which provides an opportunity for further improvement of the performance of PSCs.Conjugated polyelectrolytes have been widely used as electron injection layer in PLEDs, but not very well investigated in PSCs so far. It was first time reported by our group that polyelectrolyte as cathode interlayer could significantly enhance Voc in PSCs. In this study we found out that not only Voc, both the short circuit current （Isc） and fill factor （FF） of PSCs can be also enhanced with proper polyelectrolytes of right thickness for certain donor polymers such as PFO-DBT35 when proper polyelectrolytes were used as cathode interlayer. After a careful analysis about the function of polyelectrolytes in the device and the dark I-V curves of devices, we interpreted the origin of the Voc enhancement can be explained based on Shockley’s equation analysis.MoO₃ is an excellent anode interlayer. There are plenty of reports about using MoO₃ to increase the efficiency of PSCs, but much less investigated its effect on Voc enhancement. We replaced PEDOT:PSS with MoO₃ in devices of P3HT, MEH-PPV and PFO-DBT35. We found an increase in Voc of PFO-DBT35 （with a deeper HOMO） devices. With all the data considered, we attributed the increase in Voc of PFO-DBT35 devices not to a better ohmic contact between anode and active layer, but to a vertical phase separation caused by MoO₃.Finally, we proposed a new intermediate layer for polymer tandem solar cells with the structure of PFN/Al/MoO₃. This novel intermediate layer for tandem cell is chemically stable in air and can be easily processed. The intermediate layer shows good optical and electrical properties. With devices of a novel low band-gap conjugated polymer PBDT-DTNT as top cells, we gained a Voc as high as 1.65V, ECE exceeding 3%, and FF exceeding 50%. We believe that the performance of polymer tandem solar cells with PFN/Al/MoO₃ as intermediate layer will be enormously improved once a more suitable top cell is introduced.更多还原