基于电子快速通道的纳米电缆光阳极及电荷输运机制研究

By comparing the photovoltaic performance of dye-sensitized solar cells (DSC) with that of polycrystalline silicon solar cells, it was found that low conversion efficiency of DSSC is mainly due to the low short-circuit photocurrent density. As for DSC, the low conductivity of titania photoanode hinders the rapip charge transfer, increase the recombination rate of electron and hole pair, and thus leads to the low short-circuit photocurrent density. This project intends to develop new ultrafine Al: ZnO/TiO2 core shell nanocable photoanode, makes the outer shell and inner core play their roles, respectively. The band structure of TiO2 shell matches very well to that of dye molecules. Also, titania shell on the ultrafine Al:ZnO nanowire, with large BET surface area, can absorb dye molecules effectively. The conductivity of inner Al:ZnO core is very high, and thus can favor to the rapid charge transfer. We will investigate the effect of conductivity of inner Al:ZnO nanowire and outer titania shell thickness on the charge transfer mechanis and photovoltaic performance. By optimization, short-circuit photocurrent density of DSC is expected to increase obviously, and thus the conversion efficiency will be enhanced markedly, which is significant for developing novel photoanode of DSC and contributing to the industrilization of DSC cells.

通过对比染料敏化太阳能电池（DSC）与多晶硅太阳能电池的光电性能发现，短路电流密度偏低是DSC电池光电转换效率不高的重要原因。而DSC电池短路电流密度偏低，主要是由TiO2光阳极过低的电导率明显阻碍了导带电子的快速传递，增加了电子空穴复合产生暗反应的几率引起的。本项目针对DSC电池短路电流密度偏低的问题，拟开发新型超细Al:ZnO/TiO2芯壳纳米电缆光阳极，使外壳与内芯各司其职，即保证TiO2与染料的能级匹配、具有大比表面积（有效吸附单层染料分子），又能显著提高光阳极中电子的传导能力。通过系统研究芯壳电缆内部Al:ZnO纳米线材料电导率以及外壳TiO2膜层厚度等对DSC电池电荷输运机制和光电性能的影响，优化出最佳值，有望使DSC电池的短路电流密度大幅提高，从而显著提高DSC电池的光电转换效率，这为DSC电池新型光阳极的开发提供了新的研究思路，也对促进DSC电池的产业化具有重要意义。

本项目围绕敏化太阳能电池短路电流密度（Jsc）偏低问题，设计一维ZnO纳米阵列光阳极作为电子输运的快速通道，采用正交结构的TiO2纳米粒子对ZnO纳米棒阵列进行修饰，并且引入等离激元Ag纳米颗粒，通过光阳极界面与表面修饰以及金属的等离激元效应有效地增加了光俘获效率，减小界面电荷复合，延长电子寿命，从而提高Jsc，系统探究了界面修饰对于电荷复合和电子输运的影响机制。采用化学浴共沉积法在CdSe量子点敏化剂表面形成了Mn掺杂CdSe的钝化层，电荷复合的减少有效地提升了电池的短路电流密度Jsc和开路电压，得到高的转换效率；设计多层ZnS修饰光阳极来提高了光敏剂的负载量并减小界面电荷复合来提高Jsc；在光敏剂负载的光阳极表面沉积氧化石墨烯，虽然氧化石墨烯表面较多的缺陷增加了界面电荷复合，但其光散射效应可以有效的增加光俘获效率, 从而提高Jsc。在上述研究将显著促进提高敏化太阳能电池转换效率的科学化认识，促进其应用发展。