铜铟硒量子点敏化太阳电池中电荷复合的抑制

Quantum dot sensitized solar cell (QDSC) is one of the hot research areas among third generation solar cells due to its potential of low cost, high efficiency and good stability. CuInSe2 QDSC has obtained the highest efficiency now, while the severe charge recombination processes in this system lead to serious energy loss and restrict the improvement of the solar cell efficiency. Aiming at this crucial issue, this project will adopt several methods to inhibit charge recombination in CuInSe2 QDSC and further improve the solar cell efficiency: The alloying strategy will be used to improve the crystal quality of CuInSe2 QDs, reducing charge recombination within QDs through defect states; Photoanode coating with use of wide band gap semiconductor and insulating metal oxide materials, combining with the modification of polysulfide electrolyte by addition of polymer molecules will be carried out to inhibit charge recombination at the photoanode/electrolyte interface. Impedance spectroscopy, photo-voltage decay and transient spectroscopy techniques will be used to reveal the mechanism of the charge recombination inhibition. Finally, through the optimization and integration of several methods, the overall charge recombination processes will be inhibited significantly and the solar cell efficiency will be improved to a new level, which is among the best results in the world during the same period.

量子点敏化太阳电池（QDSC）具有低成本、高效率和长寿命的潜质，是目前第三代新型太阳电池的一个研究热点。CuInSe2 QDSC取得了该类电池目前的最高效率纪录，然而该体系中严重的电荷复合损失限制了其效率的进一步提升。针对这一制约电池效率的关键科学问题，本项目拟有针对性地采取不同措施系统化抑制CuInSe2 QDSC中的电荷复合以进一步提高该类电池效率：采用合金化的策略强化CuInSe2量子点的晶格结构，降低发生在量子点内部的电荷复合损失；采用宽带隙半导体和绝缘金属氧化物材料协同包覆光阳极形成高能垒层，以及通过向聚硫电解质中添加聚合物分子两种途径，避免裸露的光阳极与电解质直接接触，抑制发生在光阳极与电解质界面的电荷复合。通过电化学阻抗，光电压衰减以及瞬态光谱等手段揭示出抑制电荷复合的机制。最终通过对多种措施的优化整合，从整体上深度抑制电荷复合过程，获得处于同期世界先进水平的QDSC效率。

量子点敏化太阳电池（QDSC）是以量子点为吸光材料的新型太阳电池。本项目基于宽光谱吸收的I-III-VI族CuInSe2量子点吸光材料，针对“抑制电荷复合提高电荷收集效率”这一关键科学问题，通过对器件中关键界面电荷复合过程的有效调控，提高电荷收集效率及电池性能。主要取得了以下创新性成果：（1）界面性质调控新策略。通过构筑新型合金界面钝化层并采用水溶性聚合物作为界面修饰材料，显著改善了QDSC中光阳极/电解液界面性质，增大了电荷复合阻抗，有效抑制了界面电荷复合过程；（2）量子点结构和组分的创新性设计。通过核壳结构的构建以及多元合金量子点组分工程的实施，实现了QDSC中光捕获效率、电子注入效率以及电荷收集效率三者的理想平衡；（3）能带结构设计新理念。在量子点吸光层以及量子点/电解液界面引入中间能级层，通过能带结构的梯次排布，提高了QDSC中光生电子和空穴的分离效率，并进一步减少了电荷复合损失。基于以上工作，将QDSC的效率纪录由12%左右逐步提升至14%以上，继续引领了该领域的发展。在Chem. Soc. Rev., Angew. Chem. Int. Ed., Adv. Mater., Adv. Funct. Mater., J. Mater. Chem. A, Chem. Mater., J. Phys. Chem. Lett.等国际知名期刊上发表SCI论文14篇，申请发明专利3项。培养研究生5名。