硼酸提升钙钛矿太阳能电池前驱体溶液的稳定性

Boric acid improves the stability of perovskite solar cell precursor solution

钙钛矿前驱体溶液的稳定性是一个长期被忽视的问题,其对器件效率、稳定性和一致性至关重要.在甲胺甲脒复合钙钛矿体系中,溶液的不稳定性主要是由碘化甲胺的去质子化及其衍生的转亚胺基副反应造成的.在本文中,我们系统研究了不同的酸添加剂对去质子化和转亚胺基反应平衡的影响规律,发现不易于升华的硼酸具有更好的稳定效果.硼酸作为一种路易斯酸,具有sp^(2)杂化的硼原子,硼原子中未杂化的p轨道易接受一对孤对电子,从而形成配位键.在混合有机阳离子钙钛矿溶液中,B原子与I^(-)离子之间存在强的配位相互作用,可以有效抑制碘化甲胺的去质子化反应以及甲胺与碘化甲脒的转亚胺基反应,使生成副产物的含量降低了97.9%.加入硼酸稳定剂的钙钛矿前驱体溶液在老化不同时间后制备的钙钛矿薄膜和器件具有良好的重复性和一致性,这对推动钙钛矿电池的商业化进程具有重要意义.

The stability of perovskite precursor solution which is very important for device efficiency, stability and consistency has been neglected for a long time. In methylamine-formamidine complex perovskite solution, the instability of solution is mainly caused by the deprotonation of methylammonium iodide and its derived side reaction. In order to improve the stability of the solution, we systematically studied the influence of different acid additives on the balance of deprotonation and trans-methylimine reaction, and found that boric acid was the best additive. As a Lewis acid, boric acid has sp^(2)hybrid boron atoms which could accept a lone pair of electrons, thus forming coordination bonds.In the mixed organic cationic perovskite solution, there is a strong coordination interaction between B and I^(-), which can effectively inhibit the deprotonation of methylamine iodide and the transimine reaction of methylamine and formamidine iodide, resulting in a 97.9% reduction in the generated by-products. Perovskite films and devices prepared by the solution with boric acid stabilizer after aging for different times have good repeatability and consistency, which is particularly important for the commercialization of perovskite solar cells.