基于碱土金属锡酸盐光吸收材料的新型钙钛矿太阳能电池研究

The development of novel absorption materials for perovskite solar cells (PSC) with high stability in water or alcohol atmosphere and the independent intellectual property is a forefront and very difficult research area in the photovoltaic field. In this program, based on our previous research experience on the inorganic perovskite thin films, we propose to investigate a completely new perovskite absorption system, i.e., the alkaline earth stannate XSnO3（X=Ca、Sr、Ba）oxides, and develop novel PSC devices with high stability, high conversion efficiency and all-inorganic sensitizer. The XSnO3 films are to be prepared by the pulsed laser deposition and sol-gel techniques, and the doping technique with the transition metal elements (e.g., Co, Sb) is used to tune the energy band gap, including the doping of A and/or B atom and the co-doping. The aim is to prepare the perovskite films with tunable optical band gap (0.7-4.5 eV) and electronic properties. The PSC devices will be fabricated based on the further designing and optimizing of the energy level of the absorption layer and the electron/hole collecting layers. The emphasis of the work will be placed on the controllable doping technique of metal elements in the films, and the modulation method of the optical band gap, energy level and carrier transporting behavior of the film via doping. Furthermore, the effects of the interface microstructure and the cell structure on the photon-electron conversion properties, and the electron-hole recombination mechanism in the new PSC will be clarified. On the basis of a systematic understanding of the constitute materials and their working principle, we will fabricate the PSC proptotype cells, and try to improve the conversion efficiency to 10%.

开发不受环境水/醇气氛影响、具有自主知识产权的新型钙钛矿太阳能电池（PSC）光吸收材料，是当前光伏领域研究的前沿和难点。基于我们在无机钙钛矿薄膜方面的工作基础，本项目提出对全新的碱土金属锡酸盐XSnO3（X=Ca、Sr、Ba）体系光吸收材料进行攻关，研制高稳定、高效率、全无机敏化的新型钙钛矿太阳能电池。采用脉冲激光沉积、溶胶凝胶方法制备薄膜，通过对A位或B位进行过渡金属元素（钴、锑）掺杂，改变其能带结构，制备具有可调光学带隙（0.7-4.5 eV）、可调电学性能的新型钙钛矿薄膜；设计光吸收层、电子/空穴收集层的能带结构，构建新型PSC器件。重点突破金属元素可控掺杂技术，及通过掺杂调控薄膜光学带隙、能带结构、载流子输运性能的方法；重点阐明界面微观结构、器件结构对电池光电转换性能、电子-空穴再复合机制的影响规律。在此基础上，试制PSC原型器件，力争其光电转换效率突破10%。

钙钛矿结构碱土金属锡酸盐材料具有高稳定、耐高温、禁带宽度可调等特点，是新型光电材料的研究热点，应用于新型钙钛矿太阳能电池领域，预期能显著改善其耐水、不稳定等缺陷。基于此，本项目对碱土金属锡酸盐XSnO3（X=Ca、Sr、Ba）钙钛矿材料的可控制备、掺杂、光学、电学、磁学等性能进行了深入系统研究，重点探讨了金属离子Co、Cr掺杂对锡酸锶、锡酸钡外延薄膜、多孔薄膜、纳米粉体的晶体结构、微观结构、光学带隙、光催化、室温铁磁等性能的影响规律。取得主要结论如下：（1）采用脉冲激光沉积薄膜生长方法，在单晶衬底上制备了外延锡酸锶、锡酸钡薄膜，突破了金属元素的可控掺杂技术。通过掺杂钴改变了其能带结构，制备了具有光学带隙可调、电学性能可控的新型钙钛矿薄膜；所得Co掺杂SrSnO3薄膜禁带宽度在3.16-4.51 eV范围内连续可调，Co掺杂BaSnO3薄膜的禁带宽度在1.94-3.49 eV范围内连续可调。（2）采用过氧化物沉淀法制备了铬掺杂锡酸钡纳米粉体，深入探究了光生电子和空穴的生成、传输与有机物降解机制。通过Cr元素的掺杂，有效地降低了BaSnO3纳米颗粒的光学带隙，在2.69–3.15 eV范围内连续可调。并且纳米颗粒在可见光下降解有机染料的催化活性也随着Cr掺杂浓度的增加而提高。通过溶胶凝胶法制备了铬掺杂锡酸钡多孔薄膜，获得了在500-800 nm处透过率超过70%、禁带宽度低至2.68 eV、比表面积为18.98 m2/g、孔径10.75 nm的新型铬掺杂锡酸钡纳米多孔膜。采用共前驱体-溶胶凝胶法制备了锡酸钡复合氧化硅气凝胶纳米粉体，实现了纳米尺度下氧化硅凝胶骨架与锡酸钡纳米粒子的均匀复合。（3）通过流延法制备了电光/电容/红外辐射特性可调控的SiO2-TPX复合结构超材料，制备出大气窗口波段辐射率达0.91的复合厚膜，实现了在800 W/m2太阳辐照强度下比黑色表面降温20 oC、比镀银玻璃降温10 oC的冷却效果。通过溶胶凝胶法制备了具有高效废水净化的壳聚糖-氧化硅复合气凝胶材料，其吸油效率大于96%。同时，复合气凝胶还具有优异的重金属离子吸附能力，对重金属铅、铜离子的移除效率达到100%。