Gerhard Marina, Louis Boris, Camacho Rafael, Merdasa Aboma, Li Jun, Kiligaridis Alexander, Dobrovolsky Alexander, Hofkens Johan, Scheblykin Ivan G
Division of Chemical Physics and NanoLund, Lund University, Box 124, 22100, Lund, Sweden.
KU Leuven, Molecular Imaging and Photonics, Celestijnenlaan 200F, Box 2404, 3001, Leuven, Belgium.
Nat Commun. 2019 Apr 12;10(1):1698. doi: 10.1038/s41467-019-09640-w.
Organo-metal halide perovskites are promising solution-processed semiconductors, however, they possess diverse and largely not understood non-radiative mechanisms. Here, we resolve contributions of individual non-radiative recombination centers (quenchers) in nanocrystals of methylammonium lead iodide by studying their photoluminescence blinking caused by random switching of quenchers between active and passive states. We propose a model to describe the observed reduction of blinking upon cooling and determine energetic barriers of 0.2 to 0.8 eV for enabling the switching process, which points to ion migration as the underlying mechanism. Moreover, due to the strong influence of individual quenchers, the crystals show very individually-shaped photoluminescence enhancement upon cooling, suggesting that the high variety of activation energies of the PL enhancement reported in literature is not related to intrinsic properties but rather to the defect chemistry. Stabilizing the fluctuating quenchers in their passive states thus appears to be a promising strategy for improving the material quality.
有机金属卤化物钙钛矿是很有前景的溶液处理半导体，然而，它们具有多种且很大程度上未被理解的非辐射机制。在这里，我们通过研究甲基碘化铅纳米晶体中由猝灭剂在活性态和非活性态之间的随机切换引起的光致发光闪烁，来解析单个非辐射复合中心（猝灭剂）的贡献。我们提出了一个模型来描述观察到的冷却时闪烁的减少，并确定了使切换过程能够发生的0.2至0.8电子伏特的能垒，这表明离子迁移是潜在机制。此外，由于单个猝灭剂的强烈影响，晶体在冷却时显示出非常独特形状的光致发光增强，这表明文献中报道的光致发光增强的多种活化能与本征性质无关，而是与缺陷化学有关。因此，将波动的猝灭剂稳定在其非活性态似乎是提高材料质量的一种有前景的策略。
