Boosting the Photoluminescence of CsPbX3 (X = Cl, Br, I) Perovskite Nanocrystals Covering a Wide Wavelength Range by Postsynthetic Treatment with Tetrafluoroborate Salts
Boosting the Photoluminescence of CsPbX3 (X = Cl, Br, I) Perovskite Nanocrystals Covering a Wide Wavelength Range by Postsynthetic Treatment with Tetrafluoroborate Salts
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DOI：
10.1021/acs.chemmater.8b01235
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发表时间：
2018-06-12
影响因子：
8.6
通讯作者：
Samant, Anunay
中科院分区：
文献类型：
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作者：
Ahmed, Tasnim;Seth, Sudipta;Samant, Anunay
铯铅卤化物钙钛矿（CsPbX 3，X= Cl，Br，I）纳米碳近年来作为有前途的光电材料1 - 4受到了极大的关注，这是因为它们具有宽吸收、窄带宽的强光致发光（PL）、高缺陷容限和整个可见光范围内的带隙可调性。5− 7然而，这些物质的PL特性对合成条件和组成高度敏感。一些报道显示这些钙钛矿的低光致发光量子产率（PLQY）。6，8 - 14即使是通过热注入方法制备的高度发光的钙钛矿NC也不是没有缺陷的，这些缺陷充当电荷载流子的捕获中心并降低系统的PL效率。6这些NC的复杂多指数PL衰减动力学也是缺陷的结果，10，11，13，15− 19可能是由于表面20或本质上固有的。21− 23由于这些纳米碳的表面积与体积比很高，它们的PL特性在很大程度上取决于表面的质量。因此，通过合适的试剂进行表面处理是获得具有用于基于光的应用的上级PL性质的无缺陷样品的关键。在用Na/NH 4硫氰酸盐24和溴化铅处理后，观察到CsPbBr 3 NC的PLQY值接近1。19在用双十二烷基二甲基溴化铵、10双十二烷基二甲基硫化铵11和金属溴化物处理后，14、19这些NC的PLQY值达到70 - 83%。对于CsPbI_3 NC，通过用三辛基膦-PbI_2或2，2′-亚氨基二苯甲酸处理，PLQY达到约100%。因此，显然没有给定的表面处理方法对所有或大量CsPbX 3 NC有效。在我们寻求用于改善各种CsPbX 3 NC的PL性质的常用方法（合成后处理）期间，我们观察到用四氟硼酸钠/铵盐的简单处理是非常有效的。它大大增强了在400 - 600 nm区域发射的几种CsPbX 3 NC的PLQY。特别值得注意的是，CsPbBrxCl 3 − x的PLQY为90− 96%，CsPbCl 3的PLQY增强了50倍。
Cesium lead halide perovskite (CsPbX3, X= Cl, Br, I) NCs have received enormous attention in recent years as promising optoelectronic materials 1− 4 due to their broad absorption, intense photoluminescence (PL) with narrow bandwidth, high defect tolerance, and band gap tunability over the entire visible range. 5− 7 The PL properties of these substances are, however, highly sensitive to the synthetic conditions and compositions. Several reports show low photoluminescence quantum yield (PLQY) of these perovskites. 6, 8− 14 Even the highly luminescent perovskite NCs prepared by the hot injection method are not free from defects, which act as trapping centers for the charge carriers and lower the PL efficiency of the systems. 6 The complex multiexponential PL decay kinetics of these NCs is also the consequence of defects, 10, 11, 13, 15− 19 which can be due to the surface 20 or intrinsic in nature. 21− 23 Because of high surface to volume ratio of these NCs, their PL properties are largely determined by the quality of the surface. Hence, surface treatment by appropriate reagent is key to obtaining defect-free samples with superior PL properties for light-based applications.Attempts have been made previously to improve the PLQY of perovskite NCs by surface modification, during 14, 17 or after the synthesis. 10, 11, 19, 24, 25 A PLQY value of near unity is observed for CsPbBr3 NCs upon treatment with Na/NH4 thiocyanate salts 24 and lead bromide. 19 Upon treatment with didodecyldimethylammonium bromide, 10 didodecyldimethylammonium sulfide 11 and metal bromides, 14, 19 PLQY values of 70− 83% are achieved for these NCs. For CsPbI3 NCs, a PLQY of∼ 100% is achieved by treatment with trioctylphosphine-PbI2 or 2, 2′-iminodibenzoic acid. 17, 25 It is thus evident that no given method of surface treatment is effective for all or a large number of CsPbX3 NCs. During our quest for a common method (postsynthetic treatment) for improvement of the PL properties of a wide variety of CsPbX3 NCs, we observed that a simple treatment with sodium/ammonium tetrafluoroborate salt is highly effective. It enhances the PLQY of several CsPbX3 NCs emitting in the 400− 600 nm region substantially. Particularly noteworthy in this context is 90− 96% PLQY for CsPbBrxCl3− x, and 50-fold enhancement for CsPbCl3.