【作者】 王松；

【导师】 姜兆华； 吴晓宏；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2008， 博士

【摘要】 TiO₂薄膜电极是染料敏化太阳能电池的重要组成部分。制备工艺简便,成本低廉,与基体结合牢固的TiO₂薄膜电极有利于推动染料敏化太阳能电池的实际应用进程。本论文采用微等离子体氧化法在钛表面原位生长与基体结合力好和大面积的TiO₂薄膜电极。研究了电解液体系、电流密度、电压、电解质浓度、反应时间和敏化工艺对的TiO₂薄膜光电性能的影响。通过优化工艺参数实现了TiO₂薄膜电极的原位生长。以（NH4）2SO4为电解液体系,当电流密度为14A/dm2、电压为245V、电解质浓度为0.5mol/L、反应时间为10min,敏化温度为25℃,染料浓度为0.2mmol/L时,所得TiO₂薄膜电极的光电性能较好,开路电压、短路电流、填充因子和光电转换效率分别为652mV、149μA/cm2、0.39和0.095%。研究了N、S和Nd单独掺杂及N与Nd复合掺杂对原位生长TiO₂薄膜电极光电性能的影响。结果表明,N、S、Nd单独掺杂和N与Nd复合掺杂均可显著提高原位生长TiO₂薄膜电极光电性能,其中单独掺杂TiO₂薄膜电极的光电性能优于复合掺杂,N掺杂TiO₂薄膜电极的光电性能最好,开路电压、短路电流、填充因子和光电转换效率分别达到了701mV、165μA/cm2、0.42和0.121%。利用SEM、XRD、XPS、UV-vis DRS和EIS等分析手段,对掺杂前后所得TiO₂薄膜电极表面形貌、晶胞参数、晶粒大小、吸收光谱及内部阻抗进行了分析。研究结果表明,所得薄膜是由金红石型TiO₂为主晶相,同时含有少量的Ti组成,并且表面存在大量分布均匀的微孔。掺杂使TiO₂的晶胞体积发生膨胀,晶粒尺寸、禁带宽度和内部阻抗减小。其中Nd掺杂使TiO₂薄膜禁带宽度减小程度最大,而N掺杂使内部阻抗减小程度最大。通过研究原位生长TiO₂薄膜电极的光诱导电子反应和光电子界面动力学行为发现,原位生长TiO₂薄膜电极能够发生光诱导电子转移,实现光生电子的快速注入,并且较小的TiO₂晶粒尺寸和内部阻抗能够减少光生电子在界面处的湮没。利用第一性原理计算了N和Nd掺杂前后原位生长TiO₂薄膜电极的能带结构,计算结果表明掺杂后的TiO₂能带结构中产生了杂质能级,使其禁带宽度变小,计算结果与实验值符合较好,这进一步证明掺杂改性可以调节原位生长TiO₂薄膜电极的能带结构,进而提高其光电性能。探讨了原位生长掺杂TiO₂薄膜电极的光电转换行为,发现晶粒尺寸、内部阻抗和禁带宽度对原位生长TiO₂薄膜电极光电性能的影响是三者共同作用的结果,三者之间的良好匹配能够得到较高光电性能的原位生长TiO₂薄膜电极。更多还原

【Abstract】 The TiO₂ film electrode is the important part of the dye-sensitized solar cells. The development of simple production process and TiO₂ film with a strong adhesion will promote the practical application. In this paper, the TiO₂ thin film electrode with large area is in situ grown on titanium by micro-plasma oxidation.The effect of electrolyte, current density, voltage, concentration of electrolyte, time and sensitization process on photoelectric performance of thin TiO₂ film electrode is studied. The TiO₂ film electrode grown in situ has been prepared through optimizing process parameters. TiO₂ film electrode has optimum photoelectric performance in （NH4）2SO4 electrolyte when TiO₂ film is prepared under the current density of 14 A/dm2, voltage of 245 V, electrolyte concentration of 0.5 mol/L, the reaction time of 10min, sensitizing temperature for 25℃and dye concentration of 0.2 mmol/L. The open circuit voltage, short circuit current, fill factor and photoelectric transfer efficiency is 652 mV, 149μA/cm2, 0.39 and 0.095% respectivly.The effect of the N, S, Nd alone doping and N and Nd co-doping on optoelectric properties of TiO₂ film electrodes in-situ grown is studied. The results show that N, S, Nd alone doping and N and Nd co-doping can significantly increase photoelectric performance of the TiO₂ thin film electrode. Also, the photoelectric performance of the alone doped TiO₂ film electrode is superior to that of the co-doped TiO₂ film electrode and N-doped TiO₂ film electrode shows the best photoelectric performance. The open circuit voltage, short circuit current, fill factor and photoelectric conversion efficiency reaches 701 mV, 165μA/cm2, 0.42 and 0.121% respectivly.The morphology, cell parameters, grain size, absorption spectrometry and internal resistance of the TiO₂ film before and after the doping ions were analyzed by using SEM, XRD, XPS, UV-vis DRS and EIS. The results show that the film is composed of rutile TiO₂ phase and small amount of Ti and there are a lot of uniform porous on the surface of TiO₂ film. Doping ions into TiO₂ can expand the cell volume and reduces the grain size, the band gap and the internal resistance. Comparing these samples, the bandgap of Nd-doped TiO₂ film is minimum and the internal impedance of N-doped TiO₂ is minimum.The photo-induced electronic reaction and the dynamic behavior of photoelectrons in TiO₂ interface are researched. The results show that the photo-induced electron transfer and the rapid photo-electronic injection into TiO₂ film can be achieved successfully. Smaller crystal grain size and internal impedance can reduce the annihilation of the photoelectron at the TiO₂ interface.The band structure of N and Nd-doped TiO₂ electrode is calculated by the First-principles. The results show that energy bands of impurities exist in N-doped and Nd-doped TiO₂ band structure, which narrows the band gap of TiO₂ band gap. The results are in good agreement with experimental data. So, it can be conclueded that doped modification can adjust the energy band structure of TiO₂ film grow in situ, and improve the photoelectric performance of TiO₂ film.The photoelectric conversion behavior of the doping TiO₂ thin film grown in situ is discussed. It is found that the grain size, the internal resistance and the band gap affect the optoelectronic properties of TiO₂ film cooperatively. The good match among the three factors can bring the higher photoelectrode performance of thin TiO₂ film electrodes grown in situ.更多还原