Xu Yan, Xu Weidong, Hu Zhangjun, Steele Julian A, Wang Yang, Zhang Rui, Zheng Guanhaojie, Li Xiangchun, Wang Heyong, Zhang Xin, Solano Eduardo, Roeffaers Maarten B J, Uvdal Kajsa, Qing Jian, Zhang Wenjing, Gao Feng
International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
Department of Physics Chemistry and Biology (IFM), Linköping University, Linköping SE-58183, Sweden.
J Phys Chem Lett. 2021 Jul 1;12(25):5836-5843. doi: 10.1021/acs.jpclett.1c01349. Epub 2021 Jun 17.
Amines are widely employed as additives for improving the performance of metal halide perovskite optoelectronic devices. However, amines are well-known for their high chemical reactivity, the impact of which has yet to receive enough attention from the perovskite light-emitting diode community. Here, by investigating an unusual positive aging effect of CHNHI/CsI/PbI precursor solutions as an example, we reveal that amines gradually undergo N-formylation in perovskite precursors over time. This reaction is initialized by hydrolysis of dimethylformamide in the acidic chemical environment. Further investigations suggest that the reaction products collectively impact perovskite crystallization and eventually lead to significantly enhanced external quantum efficiency values, increasing from ∼2% for fresh solutions to ≳12% for aged ones. While this case study provides a positive aging effect, a negative aging effect is possible in other perovksite systems. Our findings pave the way for more reliable and reproducible device fabrication and call for further attention to underlying chemical reactions within the perovskite inks once amine additives are included.
胺类物质被广泛用作添加剂，以改善金属卤化物钙钛矿光电器件的性能。然而，胺类物质因其高化学反应活性而闻名，其影响尚未得到钙钛矿发光二极管领域的足够关注。在此，以研究CHNHI/CsI/PbI前驱体溶液不寻常的正向老化效应为例，我们揭示随着时间的推移，胺类物质在钙钛矿前驱体中会逐渐发生N-甲酰化反应。该反应由酸性化学环境中二甲基甲酰胺的水解引发。进一步研究表明，反应产物共同影响钙钛矿结晶，最终导致外部量子效率值显著提高，从新鲜溶液的约2%增加到老化溶液的≳12%。虽然这个案例研究呈现了正向老化效应，但在其他钙钛矿体系中可能存在负向老化效应。我们的研究结果为更可靠和可重复的器件制造铺平了道路，并呼吁在使用胺类添加剂时，要进一步关注钙钛矿油墨中的潜在化学反应。
