新型石墨烯基电子传输材料的制备、表征及光伏应用研究

发布时间：2018-06-02 11:06

本文选题：聚合物太阳能电池 + 电子传输材料　；参考：《苏州大学》2016年硕士论文

【摘要】：到目前为止,已报道的用于聚合物太阳能电池的电子传输材料种类较多,包括各种金属氧化物、金属氟化物以及多种有机化合物(如共轭聚电解质、n型小分子、富勒烯衍生物等)。其中,大多数无机电子传输材料存在与有机活性层兼容较差或与低成本的溶液法制膜工艺不兼容等问题。而有机电子传输材料则存在制备路径复杂、合成成本较高、稳定性较差等缺点。这些问题的存在制约了多数材料在低成本聚合物太阳能电池领域的实际应用。因此设计制备可溶液加工且低成本、高效、稳定的有机电子传输材料仍是一项很大的挑战。本论文中,我们设计制备了一种新型石墨烯-傒四羧酸钾盐复合物(rGO-K4PTC),并用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、傅里叶红外光谱(FTIR)、紫外-可见吸收光谱(UV-vis)对其进行表征。此外,紫外光电子能谱(UPS)表征表明rGO-K4PTC具有较低的功函数(3.99 eV),与K4PTC的功函(4.03 eV)相当,且明显低于rGO的功函(4.38 eV),与聚合物太阳能器件的常用受体材料PC61BM及PC71BM的LUMO能级(4.0-4.1 eV)相匹配。因此预期复合物rGO-K4PTC与小分子K4PTC作为电子传输材料可与有机活性层形成良好的欧姆接触,是一种良好的界面层材料。在应用研究中,rGO-K4PTC及K4PTC作为电子传输材料被用于构筑多种聚合物太阳能电池,包括基于P3HT:PC61BM、PTB7-th:PC61BM、PTB7-th:PC71BM体系的器件。基于rGO-K4PTC或K4PTC器件的光电转换效率分别被提高至3.03%/6.17%/7.26%和3.05%/6.18%/7.26%,相比于没有电子传输层的参比器件,最大可提升至35%,与Ca/Al标准器件的效率相当。此外,入射单色光子-电子转化效率(IPCE)测试结果表明:在波长400-650 nm区间,基于rGO-K4PTC或K4PTC的器件的IPCE值明显高于没有电子传输层的参比器件。因此,在活性层与阴极Al之间插入rGO-K4PTC或K4PTC层可以提高器件的光伏性能,这与电流密度-电压(J-V)测试结果相一致。我们进一步用原子力显微镜(AFM)表征P3HT:PC61BM/ETLs与P3HT:PC61BM活性层的表面形貌,并用空间电荷限制电流(SCLC)方法测量材料的电子迁移率。实验结果表明:(1)P3HT:PC61BM/ETLs表面粗糙度相对较低;(2)基于K4PTC或rGO-K4PTC器件的电子迁移率明显高于参比Al器件的电子迁移率。由此得出结论:插入基于K4PTC或rGO-K4PTC的电子传输层可以有效改善活性层与Al电极的接触面,从而降低器件的串联电阻(Rs),有助于提高器件光电转化效率(PCE)。更重要的是,器件稳定性测试表明:在潮湿空气中,基于rGO-K4PTC的器件比标准Ca/Al器件及基于K4PTC的器件更加稳定。可能是由于电子传输层中的rGO的存在,有效的保护了有机光活性层,减缓其在潮湿空气中的氧化和降解速度。此外,我们又初步探索了水相与有机相合成的N,P-掺杂石墨烯量子点作为空穴或电子传输材料的光伏性能。结果显示,该石墨烯量子点并不适合作为空穴传输材料,但有可能是一种潜在的电子传输材料。由于以石墨烯量子点作为电子传输层的器件效率仍低于Ca/Al标准器件效率,这方面的研究还需要进一步摸索。通过改善电子传输层制备工艺,我们预期石墨烯量子点器件的性能可以与Ca/Al标准器件相当,甚至有可能有更多提高空间。
[Abstract]:Up to now, there are many kinds of electronic transmission materials used in polymer solar cells, including a variety of metal oxides, metal fluoride and a variety of organic compounds (such as conjugated polyelectrolytes, N type small molecules, fullerene derivatives, etc.). Most of the inorganic electron transport materials have poor compatibility with the organic active layer. Or incompatible with low cost solution process membrane process, and organic electronic transmission materials have the disadvantages of complex preparation path, high synthesis cost and poor stability. The existence of these problems restricts the practical application of most materials in the field of low cost polymer solar cells. Therefore, the design preparation can be processed and low in solution. In this paper, we have designed a new type of graphene four carboxylic acid potassium salt complex (rGO-K4PTC), and used scanning electron microscope (SEM), X ray photoelectron spectroscopy (XPS), Fourier Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible absorption spectroscopy (UV-vis). In addition, the UV photoelectron spectroscopy (UPS) shows that rGO-K4PTC has a lower function function (3.99 eV), which is equivalent to the work function of K4PTC (4.03 eV), and is obviously lower than the work function of rGO (4.38 eV), which matches the common receptor material PC61BM and PC71BM LUMO energy level (4.0-4.1 eV) of the polymer solar devices. The small molecule K4PTC, as an electron transport material, can form a good ohmic contact with the organic active layer. It is a good interface layer material. In the application study, rGO-K4PTC and K4PTC are used as electronic transmission materials to construct a variety of polymer solar cells, including devices based on P3HT: PC61BM, PTB7-th:PC61BM, PTB7-th:PC71BM system. The photoelectric conversion efficiency of the rGO-K4PTC or K4PTC devices is increased to 3.03%/6.17%/7.26% and 3.05%/6.18%/7.26% respectively. Compared to the reference devices without the electronic transport layer, the maximum efficiency can be raised to 35%, and the efficiency of the Ca/Al standard device is equal. In addition, the incident monochromatic photon electron conversion efficiency (IPCE) test results show that in the wavelength 400-650 nm zone The IPCE value of the device based on rGO-K4PTC or K4PTC is obviously higher than the reference device without the electron transport layer. Therefore, the insertion of the rGO-K4PTC or K4PTC layer between the active layer and the cathode Al can improve the photovoltaic performance of the device, which is in accordance with the current density voltage (J-V) test results. We further use the atomic force microscope (AFM) to characterize P3HT:PC61. The surface morphology of BM/ETLs and P3HT:PC61BM active layer and the measurement of electron mobility by space charge limited current (SCLC) method. The experimental results show that: (1) the surface roughness of P3HT:PC61BM/ETLs is relatively low; (2) the electron mobility based on K4PTC or rGO-K4PTC devices is significantly higher than that of the reference Al device. The insertion of the electronic transport layer based on K4PTC or rGO-K4PTC can effectively improve the contact surface between the active layer and the Al electrode, thereby reducing the device's series resistance (Rs) and improving the photoelectric conversion efficiency (PCE). More importantly, the device stability test shows that in the moist air, the rGO-K4PTC based devices are more than the standard Ca/Al devices and based on K4. The device of PTC is more stable. It is probably due to the existence of rGO in the electron transport layer, which effectively protects the organic light active layer and slows down its oxidation and degradation rate in the moist air. In addition, we have initially explored the N synthesized by the aqueous phase with the organic phase and the P- doped graphene quantum dots as the photovoltaic properties of the cavitation or electronic transmission materials. The results show that the graphene quantum dot is not suitable as a hole transmission material, but it may be a potential electronic transmission material. Since the efficiency of the graphene quantum dots as the electron transport layer is still lower than the Ca/Al standard device efficiency, the research in this respect needs further exploration. By improving the preparation process of the electron transport layer, We expect that the performance of graphene quantum dot devices can be comparable to that of Ca/Al standard devices, and there may even be room for improvement.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB332;TM914.4

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