通过石墨烯杂化体系的集成构筑宽光谱太阳能电池

High-efficiency solar cells have significant importance for the sustainable development of human society. Inorganic semiconductor-conjugated polymer hybrid solar cells have obtained tremendous attention in recent years due to their low cost, high efficiency and high flexibility. It is expected that great breakthrough in the photovoltaic efficiency can be obtained if the infrared spectrum can be effectively utilized, which accounts for over 48% of the total energy of solar irradiation. One of the key problems for utilizing IR sunlight is the low efficiency in the separation of electron-hole pair generated by IR irradiation and their severe recombination, which are mainly caused by the bandoff limitaion and the low electron transfer rate. Additionally, the low transparency of the commonly used ITO electrode in the infrared region also decreases its IR utilization. Aiming at solving the above problems, this project will develop a tri-component hybrid active layer composed of graphene, low bandgap semiconductor and conjugated polymer.Based on this novel active layer and transparent conductive graphene-metal nanowire composite electrodes, a novel type of hybrid solar cell will be assembled. The separation of the electron-hole pair will be enhanced by taking advantage of the high electron affinity of graphene and high-speed electron transfer paths will be established due to the high electron mobility of graphene. Furthermore, more IR light will be transmitted into the cell due to the wide-spectrum high transparency of the graphene -based composite films.The prepared solar cells are expected to effectively utilize IR light and demonstrate remarkably improved light-to-electricity conversion efficiency.The project will mainly focuse on achieving the spectrum complementation, the band match and the efficient carrier transfer/collection by controlling the work function of hybrid graphene film, the size and energy level of semiconductors and the interfacial microstructures. This project will shed a light on the development of novel solar cells.

无机半导体-共轭聚合物杂化太阳能电池具有成本低、效率高、可制成柔性电池等优点。如能有效利用占太阳光谱48%的近红外光，将使其光电转换效率实现重大突破。目前的关键性难题是由于能带限制及电子传输慢导致窄带隙半导体产生的电子空穴对难以分离且复合严重，另一方面常规ITO透明集电极对近红外光透明性差也极大地降低了近红外光利用率。针对上述问题，本项目拟发展一种石墨烯-窄带隙半导体-聚合物三组分杂化活性层，并在金属纳米线复合石墨烯透明集电极上构建新型太阳能电池。利用石墨烯的高电子亲和势能和高电子迁移率强化电子空穴对的分离并提供电子高速传输通道，利用石墨烯复合集电极在紫外-可见-近红外宽光谱范围优异的光透过性提高近红外光射入量，从而实现电池对近红外光的最大利用。项目中主要调控半导体尺寸及能级以及界面显微结构、石墨烯复合电极光透过率及导电性以实现光谱互补和能级匹配。本项目对新型结构太阳能电池探索具有重要意义

以无机-有机杂化钙钛矿电池为代表的新型薄膜太阳能电池正得到愈来愈多的关注。本项目从透明电极及无机-有机活性层的组分及结构设计角度开展研究，以解决影响杂化太阳能电池效率及稳定性提升的关键问题。项目研制了在紫外-可见-近红外范围内均具有高透过率的石墨烯-铜纳米线复合透明导电薄膜；首次通过钒氧化物(VOx)掺杂制备了低电阻、高稳定性、高功函数的石墨烯复合透明导电薄膜，薄膜方阻较未掺杂石墨烯下降56%，达到176 Ω/□，且表现的稳定性；构筑了TiO2/石墨烯多孔结构的石墨烯柔性对电极，兼具高活性位点、高电子导电性和高效运输通道，性能与磁控溅射的Pt电极相当；制备了Y、N共掺杂的二氧化钛光阳极，提升了比表面积、表面带电量及氧空位，电极的载流子输运性能大幅提高，电池效率提升18%；构筑了基于Cs-TiO2致密层的新型钙钛矿太阳能电池，Cs掺杂提升了致密层覆盖度且通过能级调控提高了电池的开路电压，整体光电转换效率提高了9%；首次采用溶剂-溶剂萃取法制备多孔PbI2薄膜，生长出具有大晶粒且形貌可控的高质量钙钛矿膜；将两步法制备钙钛矿薄膜的时间由10min缩短到40 s；同时，构筑的双层电池效率从5.9%提高到10.1%；创新性地提出了采用不完全结晶多孔PbI2（ln-PbI2）辅助增强固相反应生长柱状晶钙钛矿膜的方法，制备的钙钛矿电池的光电转换效率达到16.4%且迟滞现象更弱，还提出了一种基于V_Pb^"辅助Pb2+跳跃的模型；同样以Ln-PbI2为基础，在低至75 oC条件下通过固相反应法制备了高质量CH3NH3PbI3膜，构建的钙钛矿电池最高效率为13.8%，该方法对降低能耗及实际生产应用有重要意义；首次提出利用兼具强极性与高沸点的非配位型溶剂气氛，促进薄膜的奥斯瓦尔德熟化，使低温固相反应制备的钙钛矿太阳能电池效率进一步提升至15.1%。项目在J. Power Sources, Applied Surface Science等期刊发表SCI论文12篇，授权中国发明专利4项。