瑞典林雪平大学高峰&刘小可等：钙钛矿晶格重构实现高亮度、卓越的颜色稳定性及低效率滚降的混合卤化物蓝色钙钛矿发光二极管
文摘
科学
2024-10-23 09:49
北京
近日，瑞典林雪平大学高峰教授和刘小可副教授等人在Science China Materials发表研究论文，展示了一种简单、有效且通用的晶格重构方法，利用具有高古特曼供体数（DNs）的非极性溶剂来提高钙钛矿薄膜的质量。
本文要点
1) 发现高DN非极性溶剂，例如乙酸乙酯，可以与钙钛矿前驱体相互作用。这种溶剂可以使钙钛矿晶格更加有序和“更坚硬”，并促使钙钛矿表面形成一种2D/3D的钙钛矿异质结构。2) 晶格重构的钙钛矿薄膜表现出较低的缺陷密度并且其钙钛矿离子迁移受到了抑制。最终得到的混合卤化物蓝色钙钛矿发光二极管（PeLEDs）显示出极高的驱动电流密度和电压的耐受性，表现出高亮度和卓越的颜色稳定性。本工作深入研究了非极性溶剂与钙钛矿相互作用，并为进一步开发高性能的PeLEDs提供了启发。Figure 1. Physical properties of the control and lattice-reconstructed perovskite films. (a) Schematic of the lattice reconstruction approach. (b) Top-view SEM images. (c) GIWAXS plots integrated over all angles (the inset shows an enlarged plot around q = 15 nm−1). (d) PL spectra. (e) Time-resolved PL decays. (f) Variation of PL maximum peak energy with temperature (the solid lines are fittings). (g) Arrhenius plots of temperature-dependent FWHM (the solid lines are fittings). (h) UPS spectra.![]()
Figure 2. A serious of characterizations for comprehensive understanding of the perovskite lattice reconstruction process. (a) In-situ GIWAXS measurement for perovskite lattice reconstruction. (b) Photographs of FABr and PbBr2 powders (upper panel) as well as CsBr and PbBr2 powders (lower panel) in CB, DE, EA, and DMSO, respectively. (c) The dielectric constant and DNs of common solvents used in perovskite research. IPA, DMF, GBL and NME are isopropanol, N,N-dimethylformamide, 1,4-butyrolactone and nitromethane, respectively. (d) XRD patterns of the orangish red powder generated by soaking FABr and PbBr2 powders in EA. * and # peaks are assigned to FAPbBr3 and FAPb2Br5 phases, respectively. (e) PL spectrum of the orangish red powder. (f) UV-vis spectra for the control, lattice-reconstructed, and EA soaking perovskite films. High-resolution O 1s XPS spectra for (g) control and (h) lattice-reconstructed perovskite films. (i) FTIR spectra of the EA solvent as well as control and lattice-reconstructed perovskite films. The wavenumber of 1750 cm−1 is the stretching vibration of C=O of EA, while 1710 cm−1 is attributed to the stretching vibration of C–N coming from the FA of perovskite. The red dashed line implies the ν(C=O) of EA shifted from 1750 to 1730 cm−1.![]()
Figure 3. PeLEDs performances for control and lattice-reconstructed devices. Histograms of (a) peak EQE and (b) peak luminance for control and lattice-reconstructed devices. (c) Current density–voltage–luminance characteristics and (d) EQE-current density curves for representative PeLEDs. The plots of CIEy versus applied (e) current densities and (f) voltages. Nyquist plots of the impedance spectra for (g) control and (h) lattice-reconstructed perovskite films. (i) Temperature-dependent conductivity characteristics for control and lattice-reconstructed perovskite films.Jionghua Wu, Renjie Wang, Rui Zhang, Giuseppe Portale, Eduardo Solano, Xiaoke Liu, Feng Gao. Lattice reconstruction for mixed-halide blue perovskite light-emitting diodes with high brightness, outstanding color stability and low efficiency roll-off. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3080-5
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