Dobrovolsky Alexander, Merdasa Aboma, Li Jun, Hirselandt Katrin, Unger Eva L, Scheblykin Ivan G
Chemical Physics and NanoLund, Lund University, P.O. Box 124, 22100 Lund, Sweden.
Young Investigator Group Hybrid Materials Formation and Scaling, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Albert-Einstein Strasse 16, 12489 Berlin, Germany.
J Phys Chem Lett. 2020 Mar 5;11(5):1714-1720. doi: 10.1021/acs.jpclett.9b03878. Epub 2020 Feb 18.
Nonradiative losses in semiconductors are related to defects. At cryogenic temperatures, defect-related photoluminescence (PL) at energies lower than the band-edge PL is observed in methylammonium lead triiodide perovskite. We applied multispectral PL imaging to samples prepared by two different procedures and exhibiting 1 order of magnitude different PL quantum yield (PLQY). The high-PLQY sample showed concentration of the emitting defect sites around 10-10 cm. No correlation between PLQY and the relative intensity of the defect emission was found when micrometer-sized local regions of the same sample were compared. However, a clear positive correlation between the lower PLQY and higher defect emission was observed when two preparation methods were contrasted. Therefore, although the emissive defects are not connected directly with the nonradiative centers and may be spatially separated at the nano scale, chemical processes during the perovskite synthesis promote/prevent formation of both types of defects at the same time.
半导体中的非辐射损耗与缺陷有关。在低温下，在甲基铵碘化铅钙钛矿中观察到能量低于带边光致发光（PL）的与缺陷相关的光致发光。我们将多光谱PL成像应用于通过两种不同程序制备的样品，这些样品表现出相差1个数量级的PL量子产率（PLQY）。高PLQY样品显示发射缺陷位点的浓度约为10-10厘米。当比较同一样品的微米级局部区域时，未发现PLQY与缺陷发射的相对强度之间存在相关性。然而，当对比两种制备方法时，观察到较低的PLQY与较高的缺陷发射之间存在明显的正相关。因此，尽管发射缺陷与非辐射中心没有直接联系，并且可能在纳米尺度上在空间上分离，但钙钛矿合成过程中的化学过程同时促进/阻止了这两种类型缺陷的形成。
