CuInS2量子点/ZnO纳米晶阵列异质界面的结构调控及电荷转移机理研究

At present, the quantum-dot-sensitized solar cell (QDSC) based on ZnO nanostructures exhibits a low photoelectric conversion efficiency. This is largely because, ZnO nanorods/wires array used as photoanode has a higher proportion of low-energy facets exposed where the formed heterointerface between quantum dots and ZnO shows a weak bonding, easily leading to difficulties in the charge transfer at the interface, and thus increasing the recombination rate of photo-generated carriers. To solve this problem, the exposed facets of ZnO and their proportion will be adjusted by solution processing method in situ on the conductive glass according to the face-selective electrostatic control theory. The heterointerface between CuInS2 quantum dots and ZnO nanocrystals array will be formed by in situ synthesis. The structure of the heterointerface will be controlled by varying experimental parameters. The process of photo-generated charge transfer in the obtained heterointerface will be investigated by electrochemical impedance spectroscopy (EIS) and time-resolved photoluminescence spectroscopy. Moreover, the influence of heterointerface with different structures on the photo-generated charge transfer and the performance parameters of solar cell will be revealed. And also the charge transfer mechanism in the heterointerface will be established. Basing on the above results, our project will supply theoretical direction to optimize the cell performance of QDSC based on ZnO.

目前ZnO基量子点敏化太阳能电池(QDSC)的光电转换效率较低，其重要原因是作为光阳极的ZnO纳米棒/线阵列具有较多比例的低能暴露晶面，在该晶面上形成的量子点/ZnO异质界面具有较差的结合力，易导致该界面处的电荷转移困难，增加光生载流子复合几率。针对这一问题，本项目将根据ZnO晶面静电控制作用，采用溶液处理法在导电玻璃表面原位调节ZnO纳米晶阵列的暴露晶面及其所占比例，采用原位合成法制备CuInS2量子点/ZnO纳米晶异质界面并调节实验参数以调控该异质界面的结构，采用电化学阻抗谱和时间分辨荧光谱来研究该异质界面处的光生电荷转移过程，揭示具有不同结构特征的异质界面对光生电荷转移过程、电池各性能参数的影响规律，建立异质界面的电荷转移机制，这些研究将为ZnO基量子点敏化太阳能电池的性能优化提供理论指导。

ZnO基量子点敏化太阳能电池的光电转换效率较低，主要是由于作为光阳极的ZnO纳米棒阵列具有较高比例的低能暴露晶面（10-10），而该晶面与量子点的结合力较差，使得该界面处的光生电荷转移困难，增加光生载流子复合几率，从而降低太阳能的光电流和光电转换效率。本项目针对这一问题，考虑到ZnO纳米晶阵列的高能暴露晶面（0001）很可能与量子点结合会更紧密，设计制备可在导电玻璃表面原位调节ZnO纳米晶阵列的暴露晶面及其比例的方法，研究了ZnO纳米晶的形成机理、暴露晶面调控方法和CuInS2量子点敏化到ZnO纳米晶的光电性能。通过本项目的执行，发展了原位调控ZnO纳米棒阵列暴露晶面及其比例的溶液处理法和形成机理，调控了CuInS2量子点的尺寸并改善了该量子点的分散性和稳定性，探明了CuInS2量子点敏化到ZnO纳米晶阵列的可行途径，提高了光阳极ZnO的光电流，并研制出了光电转换效率较高的量子点敏化太阳能电池。此外，我们还制备了多孔ZnO纳米棒阵列和高能暴露晶面为（0001）的ZnO中空微球，并探究了其形成机理和催化性能，为太阳能电池的光阳极提供了更多的选择性。本项目部分研究结果在Solar Energy Materials and Solar Cells、CrystEngComm、Physical Chemistry Chemical Physics、ACS Applied Materials & Interfaces和Ceramics International等国际著名期刊上发表8篇学术论文，申请了3项国家发明专利（2项已授权）。这些研究结果将为量子点敏化太阳能电池的发展和应用提供理论指导。