Degradation of Highly Alloyed Metal Halide Perovskite Precursor Inks: Mechanism and Storage Solutions
Degradation of Highly Alloyed Metal Halide Perovskite Precursor Inks: Mechanism and Storage Solutions
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DOI：
10.1021/acsenergylett.8b00305
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发表时间：
2018-04-01
影响因子：
22
通讯作者：
van Hest, Maikel F. A. M.
中科院分区：
文献类型：
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作者：
Dou, Benjia;Wheeler, Lance M.;van Hest, Maikel F. A. M.
尽管金属卤化物钙钛矿 (MHP) 光伏 (PV) 的前景在于它们可以将高效率与溶液加工性结合起来，但前驱体油墨中发生的化学反应在很大程度上尚未被探索。在此，我们研究了基于最广泛使用的溶剂二甲基甲酰胺 (DMF) 和二甲基亚砜 (DMSO) 的 MHP 溶液的降解情况。对于所研究的 MHP 油墨，其中含有甲脒 (FA(+))、甲基铵 (MA(+))、铯 (Cs+)、铅 (Pb2+)、溴化物 (Br-) 和碘化物 (I-)，在黑暗中将油墨储存在氮气中后，观察到显着的成分变化。我们发现，前驱体溶液中 DMF 水解形成甲酸二甲铵，随后融入 MHP 薄膜中，从而损害 Cs+ 和 MA(+) 稳定 FA(+) 基 MHP 的能力。溶液化学的变化导致钙钛矿薄膜化学计量、带隙和结构的改变。当球磨成粉末时，固体前体盐是稳定的，允许储存大量化学计量的前体材料。
Whereas the promise of metal halide perovskite (MHP) photovoltaics (PV) is that they can combine high efficiency with solution-processability, the chemistry occurring in precursor inks is largely unexplored. Herein, we investigate the degradation of MHP solutions based on the most widely used solvents, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). For the MHP inks studied, which contain formamidinium (FA(+)) methylammonium (MA(+)), cesium (Cs+), lead (Pb2+), bromide (Br-), and iodide (I-), dramatic compositional changes are observed following storage of the inks in nitrogen in the dark. We show that hydrolysis of DMF in the precursor solution forms dimethylammonium formate, which subsequently incorporates into the MHP film to compromise the ability of Cs+ and MA(+) to stabilize FA(+)-based MHP. The changes in solution chemistry lead to a modification of the perovskite film stoichiometry, band gap, and structure. The solid precursor salts are stable when ball-milled into a powder, allowing for the storage of large quantities of stoichiometric precursor materials.