基于量子点超晶格的多激子太阳电池：高能光子的高效利用

This project proposes a quantum dot superlattice as a photoactive layer to convert one high energy photon into multiple excitons, which is an almost fully new exploration. It aims at overcoming the insufficient utilization of those high energy photons of current solar cells by introducing this carrier multiplication effect. The microstructures of the complex superlattice film will be effectively controlled via various synthetic approaches in a bid to enhance the wave function coupling of adjacent quantum dots and thereby leading to a fast transfer of excitons generated from high energy photons from one quantum dot to its neighboring dot. The rapid exaction transfer between adjacent quantum dots will be a promising resolution to the short-lived excitons which are hard to be extracted, because the density of excitons in a single quantum dot is greatly reduced in this circumstance, which leads to a suppressed the Auger recombination and an extended lifetime of the excitons. Using femtosecond transient absorption spectroscopy rigorously calibrated for the number of absorbed photons, the inner relationship between the microstructures of the quantum dot superlattice and the exciton generation/ dissociation/transfer will be unveiled. The underlying laws and approaches for highly efficient utilization of high energy photons will be elucidated. The scientific problems confronted with multiple exciton generation solar cell assembly, along with the design of device prototypes will be overcome, which will elevate the self-innovation capability of China. This project will promote interdisciplinary developments such as optoelectronic informatics, optoelectronic materials and ultrafast photonics.

本项目提出以量子点超晶格为光吸收层，将一个高能光子转换为多个激子，产生载流子倍增效应，以期解决现有太阳电池器件对高能光子利用率不足的问题，这是一项近乎全新的探索。采用多种成膜技术可控制备量子点超晶格/TiO2复合膜，调控其微纳结构参量，增强量子点间波函数耦合作用，进而将高能光子产生的多激子快速转移至邻近量子点。这种点间激子快速转移使单个量子点内激子浓度大幅降低，可抑制俄歇复合效应、延长多激子的寿命，有望解决激子消逝过快较难提取利用的问题。以定量化的飞秒瞬态吸收光谱技术为手段，探明量子点超晶格微观结构与多激子产生、分离及传输之间的内在联系。揭示提高高能光子利用有效途径和规律，解决多激子太阳电池器件研制的科学技术问题，提供高效的太阳电池器件，获得创新性的研究成果。本项目对推动光电信息学、光电材料学、超快光子学等相关学科的交叉与发展具有重要的意义。

本项目获批以来，围绕项目预定目标，项目团队合成了一系列具有功能特异性的量子点材料，表征了量子点材料各项性能，揭示其控制规律，达到调控量子点能级结构、能带及带隙等性能参数的目的；制备了新型高质量的量子点薄膜，采用多种工艺条件控制，解决器件薄膜化带来的量子点薄膜量子产率极度下降等问题；实现了合适的无机受体材料，确定了可控制备基于有机/无机新型体异质结优化方案；开发了电子阻挡层材料，阻挡了多余电子的注入使电子空穴传输具有优异的平衡性能，提升了外量子效率。实现光电子器件的新型体异质结的可控制备，获得高光电转换效率的光电子器件。探明新型体异质结电子/空穴产生、分离及传输的规律，通过对比和评价器件的电子/空穴俘获性能，反馈材料制备，确定提高光电子器件光电性能的有效途径和规律；抑制俄歇复合效应，提高激子利用率，为高效多激子量子点太阳电池奠定坚实的基础。. 在项目的执行期间，项目负责人发表已标注本项目基金支持的相关学术论文30余篇。申请国家发明专利11项，授权发明专利3项。依托此项目的顺利开展，在项目实施的四年时间里，项目负责人获批团队项目和省科技项目3项。以第一指导老师指导本科生获得“挑战杯”、“互联网+”创新创业竞赛省赛以上奖励3项。以第一和主要完成人荣获省自然科学二等奖1项和教育部高等学校优秀科研成果二等奖1项。本项目的研究目标均已达到，多项指标超额完成，并取得了一系列科研成果。