高效稀土掺杂Na5Lu9F32上转换发光单晶体的研究

In order to overcome the difficulties in the current low power conversion efficiency (PCE) of single-junction solar cells such as perovskite solar cell induced from the inability of them to absorb the near infrared (NIR) light from 800 to 1700nm, the project aims to investigate rare earth ions such as Yb3+/Er3+ doped transparent big size Na5Lu9F32 fluoride single crystals with strong broad band absorption in the range of NIR and efficient upconversion (UC) of high energy visible emission. We intend to study the growth parameters of the multi-rare earth doped fluoride single crystals, and the relation between the optical absorption in the range of NIR, visible upconversion and doping concentration, doping rare earths. The optimum spectrum will be realized in terms of identifying the mechanisms and affecting factors for optical upconversion of rare earth ion which can be identified from their optical spectra. Furthermore, when the single crystal is inserted into the perovskite solar cells, the PCE of the cells will also be investigated under the irradiation of simulated sunlight. It is expected that the PCE is enhanced obviously because we used the UC crystal which can convert the NIR light to visible light within the response of perovskite solar cells. Finally, this project will provide a technology foundation to the research and productization of the novel efficient solar cell, and exploitation and utilization of green and renewable energy generation in the future.

针对目前钙钛矿等单结太阳能电池缺乏对800-1700nm近红外波段光线有效吸收，而导致其太阳能转换效率低下这一问题，本项目拟开展一种可有效实现高效近红外宽带吸收与上转换可见光发射的Yb3+/Er3+等多稀土掺杂Na5Lu9F32大尺寸新型透明氟化物单晶体研究。研究多种稀土离子掺杂单晶体的坩锅下降法生长条件、晶体的近红外吸收与上转换可见发光特性及稀土离子的掺杂浓度与种类的关系。通过光谱特性研究上转换发光机理及其影响因素，并实现优化的光谱性能。以此晶体为基础的上转换器插入到太阳能电池中，研究太阳光辐照下电池的能量转换效率。该新型的上转换器的使用可望把近红外光有效地转换成电池响应敏感的可见光，并显著提高钙钛矿太阳能光伏电池的能量转换效率。本项目研究工作对探索新型高效太阳能电池与绿色可再生能源的开发与利用具有重要意义。

本项目开展了一类具有强上转换发光性能的Yb3+/Er3+多稀土掺杂Na5Lu9F32大尺寸透明氟化物单晶体的研究，并探索其在太阳能光伏以及其它光电子领域中的可能应用。采用铂金坩埚全密封的坩埚下降法技术，在绝水、绝汽的生长环境下，有效地防止了高温状态下氟化物原料与水的反应以及氟化物气体对设备的强力侵蚀和人体的可能伤害，成功地生长出高质量的稀土离子掺杂氟化物单晶体。在5.5wcm−2 强度的980nm光激发下,测得1.0mol%Er3+/8.0mol%Yb3+掺杂Na5Lu9F32外量子效率接近6.80%。在太阳光（7-8太阳常数）辐照下，通过外加该单晶为转换器，可提高15.5%的太阳光转化为电能。该新型的上转换器的使用可把近红外光有效地转换成电池响应敏感的可见光，并显著提高钙钛矿太阳能光伏电池的能量转换效率。由于该类单晶体材料优异的物化性能、热温稳定性、机械可加工性能以及高的上转换光学效应，研究结果为提高钙钛矿型太阳能电池的性能提供一种有效的途径与方法。