基于银纳米线柔性透明导电薄膜的染料敏化太阳电池界面过程研究

Dye sensitized solar cells (DSCs) have attracted broaden interest for the relatively high photo-to-energy conversion efficiency and low production cost. Improvement in flexibility of DSCs could make them more applicable. The commonly used transparent and conductive films like F-doped tin oxide (FTO) and Indium tin oxide (ITO) have been known to show poor flexibility, thus are not suitable for use in flexible DSCs. Silver is known to show excellent conductivity and ductility. Silver nanowires (AgNWs) derived transparent conductive film is easy to be fabricated. Based on theoretical calculation, the film could reach excellent performance (90% for transmittance, 1.6 ohm/sq for sheet resistance) at quite low silver loading or 0.1g per square meters on substrate. We here use AgNWs based transparent and conductive films to fabricate flexible DSCs at low temperature (<130 C), so as to upgrade the flexibility and lower fabrication cost of DSCs. In order to enhance the ability of AgNWs both in anti-oxidization and anti-corrosion, a blocking layer will be added to interface between AgNWs and photoanode(also electrolyte). We will firstly study the effect of coverage of AgNWs on films, connectivity and contact resistance between the nanowires on as-fabricated transparent and conductive films; and then explore the effect of microstructure and energy level structure on the charge transfer and recombination processes across the interfaces of "AgNWs/blocking layer/photoanode(also electroyte)", so as to clarify the important role played by back electrode in photo-to-electric conversion processes of DSCs; and at last, we looking forward to fabricate flexible electrode with 90% in transmittance and 5 ohm /sq in sheet resistance, and assemble flexible DSCs with efficiency up to 6.0%.

染料敏化太阳电池（DSCs）因光电转换效率高、制备成本低而备受关注，柔性化有助于拓宽电池应用领域。FTO、ITO透明导电薄膜柔性差。银纳米线（AgNWs）透明导电薄膜柔性强、成本低，在极低的银负载量下（0.1克/平方米）透光度达90%、方阻达1.6 ohm/sq。本项目采用AgNWs柔性透明导电薄膜在低温下(<130 C)制备DSCs，以提高器件柔性，降低制备成本。在AgNWs与光阳极（电解质）界面增加阻挡层，以提高AgNWs抗氧化腐蚀性，抑制电荷界面复合。研究AgNWs表面覆盖率、联通度以及线间接触电阻对薄膜透光导电性能的影响规律；研究"AgNWs/阻挡层/光阳极（电解质）"界面微观结构与能级结构对界面电荷传输与复合过程的影响规律；明确底电极在DSCs光电转换过程中的重要作用。通过以上研究，使AgNWs透明导电薄膜的透光度达90%、方阻达5ohm/sq，器件效率达6.0%。

金属银纳米线网格具有优异的透光导电性能与抗弯曲疲劳性能。根据前期在金属银纳米线生长与染料敏化太阳电池方面的研究经验，本项目围绕超长金属银纳米线合成与生长机制，透明导电网格制备、透光导电机制及抗弯曲疲劳机制，染料敏化太阳电池光管理与光电转换效率等方面开展研究。获得研究成果如下：（1），实现采用一步溶剂热法合成长度超过460微米的金属银纳米线，揭示了氧气O2与氢离子（H+）之间的协同氧化腐蚀行为在金属银纳米线生长过程中所起的关键作用；（2）通过高温退火（200摄氏度）制备出透过率（550纳米）92.1%，方阻12.6ohm/sq的透明导电薄膜；（3）通过搅拌增强腐蚀行为获得了超直金属银纳米线，并采用偏心旋转法制备出定向排列的纳米线阵列，借以研究了该阵列的偏振光透过率特性；（4），发现金属银纳米线具有良好的抗弯曲疲劳性能，发现在半径2mm下弯曲512次不仅不会降低导电性，反而有利于增强纳米线之间的接触，从而降低接触电阻；采用该方法在室温下制备的金属银纳米线透明导电薄膜，获得了90%（@550纳米），12.5ohm/sq的透光导电性能，优于市场上购买的柔性ITO透明导电薄膜；（5），发现金属银纳米线可以用来制备低温高导电银浆；（6），采用冰模板法制备出具有开放式孔径结构的TiO2纳米晶薄膜，该结构有利于增强光散射，从而增加太阳电池光吸收与光电流; （7），采用导电碳薄膜作为顶电极制备了稳定高效的钙钛矿太阳电池，其效率达到11% （AM1.5G， 1sun）。.以上研究证明，通过超长金属纳米线的生长与接触电阻的降低，可以在低温下获得高透光导电性能的柔性导电基底。同时，通过薄膜孔隙结构调控有助于提高太阳电池的光吸收。该项目的成功实施为金属银纳米线在柔性透明导电基底领域的应用打下了坚实的理论与实验基础，项目初步实现了申请目标。