基于PIN结构的高效PbS量子点太阳能电池研究

Lead sulfide quantum dots (PbS QDs), possessing advantages such as tunable bandgap, capability of achieving >44% efficiency in theory in single junction solar cells, broadened absorption into infrared, and high compatibility with low-temperature roll-to-roll manufacturing process, have attracted much attention in the research field of optoelectronic recent years. Based on the first-class research platform at Wuhan National Laboratory for Optoelectronics and the rich research experiences on QDs of Prof. Jiang Tang’s group, the applicant have already obtained a PIN PbS QDs solar cell with power conversion efficiency of 9.0%. However, low carrier mobility and fill factor still limit device efficiency of QDs solar cells. In this project, we plan to improve the efficiency to 11.5%, a world-class efficiency, though the following five strategies: .1) Obtain high quality QDs with low surface defect density though ion exchange fabrication method and halogen ion passivation, thus improving carrier lifetime;.2) Develop graphene doped PbS QDs film with higher carrier mobility;.3) Replace hole collection layer (EDT treated PbS layer) with materials with high carrier concentration and mobility to improve the carrier transport and collection efficiency;.4) Introduce high-resistance layer at the junction interface to reduce interfacial defects；.5) Employ depleted bulk heterojunction and molecular dipoles to enhance the carrier separation and collection efficiency.

PbS量子点具有带隙可调及单结太阳能理论效率达44%的优势，并可将吸收光谱拓宽到红外波段，适合低温卷到卷低成本生产，是近年来光电领域研究的热点和前沿。依托武汉光电国家实验室先进的研究平台，结合唐江教授课题组丰富的PbS量子点研究经验，申请人已经获得了光电转换效率为9%的PIN结构PbS量子点太阳能电池。但是仍然存在量子点迁移率低、器件填充因子差的瓶颈。本项目拟从如下五个方面着手，以期获得光电转换效率为11.5%的量子点太阳能电池，达到国际一流水平：.1）通过离子交换、卤素离子钝化等方法降低量子点表面缺陷密度，提高载流子寿命；.2）发展石墨烯掺杂的PbS量子点薄膜，进一步提高迁移率； .3）利用高掺杂浓度和迁移率的空穴收集层提高光生载流子的收集效率；.4）引入界面高阻层，减少复合损失；.5）通过体异质结和界面双电层的构筑，提高光生载流子的分离和收集效率。

PbS量子点具有带隙可调及单结太阳能理论效率达44%的优势，并可将吸收光谱拓宽到红外波段，适合低温卷到卷低成本生产，是近年来光电领域研究的热点和前沿。研究工作通过改进窗口层薄膜的掺杂浓度、降低界面缺陷态密度、优化量子点表面的配体交换工艺，提高量子点薄膜载流子浓度和迁移率等方法，将PbS量子点薄膜太阳能电池的光电转换效率提升到了10.6%。研究结果表明，氯掺杂氧化锡能够达到钝化PbS量子点与窗口层界面缺陷，降低界面复合损失的目的；1-乙基-3甲基碘化咪唑鎓作为量子点的交换配体，可以实现量子点表面缺陷的钝化；将Ag掺杂到PbS量子点薄膜中，可以实现对量子点薄膜的载流子浓度，迁移率以及能带结构的有效调控，从而提高了光生载流子的分离和收集效率，将PbS量子点太阳能电池的光电转换效率提升到10.6%，达到国际一流水平。此外，对PbS量子点的尺寸、配体处理工艺等对其能带结构和迁移率的影响进行了系统的研究，为后后续进一步提高器件性能提供了理论依据。本项目对PbS量子点太阳能电池窗口层、界面、吸光层以及PbS量子点作为空穴收集层进行了系统的研究和优化，为PbS量子点太阳能电池效率的进一步提升奠定了坚实的基础。在上述工作中，发表高水平SCI论文8篇，培养硕博研究生4名。