新型锡(II、IV)复合非铅钙钛矿光伏材料与器件研究

Hybrid perovskite photovoltaic efficiency has reached 22.1%. For practical application, it has to be solved the problem of heavy metal lead substitution. Therefore, the project focus on this key scientific issues by designing and preparing new non-lead perovskite materials, in order to achieve efficient photovoltaic devices. In view of the suitable energy gap and high carrier mobility of the divalent tin perovskite material, it is easy to be oxidized and unstable, while the tetravalent tin perovskite material has good chemical stability, but there are vacancy defects. The combination of divalent tin and tetravalent tin materials are Sn(II, IV) composite of new non-lead perovskite materials, such as the ratio of 1: 1 A3Sn (IV) Sn (II) X9. The project: 1) with organic ions, new perovskite such as Csx(CH3NH3) 2-xSnI6, (CH3NH3) 2SnI6, etc . can be achieved with better film quality and absorption to sunlight; 2) through the divalent tin doping, to improve the absorption capacity of tetravalent tin perovskite materials and film-forming, such as Csx (CH3NH3) (II, IV) composite non-Pb perovskite materials; (3) to study the photovoltaic properties of Sn (II, IV) composite non-lead perovskite materials, and to study the photographic properties of tin (II, IV). The aim is to achieve a breakthrough in photovoltaic efficiency of 15%.

杂化钙钛矿的光伏效率已经达到22.1%，但要实用化必须解决重金属铅的替代问题。故本项目将围绕这一关键科学问题，设计与制备新型锡（II,IV）复合的非铅钙钛矿材料，实现高效的光伏器件。基于二价锡的钙钛矿材料合适的能隙及高载流子迁移率，但容易被氧化而不稳定，而四价锡钙钛矿材料化学稳定性好，但有空位缺陷，吸光能力稍弱，本项目结合二价锡与四价锡材料的优点，设计锡（II,IV）复合的新型非铅钙钛矿材料，如按照1:1的比例复合即得到A3Sn(IV)Sn(II)X9的非铅钙钛矿材料。主要1)通过有机阳离子的掺杂，改善四价锡钙钛矿材料的吸光能力及成膜性，如Csx(CH3NH3)2-xSnI6，(CH3NH3)2SnI6等；2)进一步通过二价锡掺杂四价锡钙钛矿，改善其吸光能力，设计锡（II,IV）复合的新型非铅钙钛矿光伏材料；3）研究锡（II,IV）复合型非铅钙钛矿材料的光伏性能，实现光伏效率突破15%。

针对卤化物钙钛矿中重金属铅的替代问题，选取非铅钙钛矿中锡基钙钛矿与铋基钙钛矿为研究对象，通过掺杂改善非铅钙钛矿的成膜性能（电学性能）及吸光能力（光学性能）。项目主要研究了1)非铅钙钛矿及其掺杂的成膜性能，通过掺杂具有类似结构的铋基双钙钛矿能够提升四价锡基钙钛矿的成膜性能；通过掺杂Li盐，极大改善AgBiIx三元铋基钙钛矿的成膜性能，实现无针孔非铅钙钛矿薄膜的制备，使得光伏器件的Voc从0.6V极大提升到0.9V；2）通过二价锡掺杂四价锡钙钛矿以及铋基双钙钛矿掺杂改善吸光能力，铋基双钙钛矿A位掺杂对其吸光能力改善有限，基于B位掺杂能极大改善其吸光能力，发现通过掺杂1%Fe代替Bi3+，形成中间带，使得非铅双钙钛矿的吸收扩展到最长近红外区域(≈1350 nm)；3）钙钛矿材料光伏性能，基于四元铋基钙钛矿的半透明紫外阻挡光伏器件在平均可见透过率为72.5%的情况下，其效率达1.6%；AgBiIx三元铋基非铅钙钛矿材料，其光伏效率达到2.8%。通过对陷光结构的钙钛矿太阳能电池进行数值模拟，结果显示陷光结构比同样厚度的平面结构可以提升30%以上的吸光效率，显示陷光结构在非铅电池中应用的前景。