Valence and Conduction Band Densities of States of Metal Halide Perovskites: A Combined Experimental-Theoretical Study.
Valence and Conduction Band Densities of States of Metal Halide Perovskites: A Combined Experimental-Theoretical Study.
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DOI：
10.1021/acs.jpclett.6b00946
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发表时间：
2016-07-21
期刊：
影响因子：
--
通讯作者：
Kahn A
中科院分区：
文献类型：
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作者：
Endres J;Egger DA;Kulbak M;Kerner RA;Zhao L;Silver SH;Hodes G;Rand BP;Cahen D;Kronik L;Kahn A
报道了用紫外光和反向光电子能谱测量了三种金属卤化物钙钛矿的价态和导带密度，特别是在不同衬底上生长的三种金属卤化物钙钛矿，特别是甲基溴化铅和溴化铅和溴化铯铅(MAPbI3，MAPbBr3，CsPbBr3)。并与密度泛函理论计算的理论态密度(DOS)进行了比较。实验和理论之间的定性一致导致了价带和导带光谱特征的识别，并允许精确地确定材料的带边位置、电离能和电子亲和力。比较发现，这些化合物在价带最大值(VBM)处有异常低的DOS，这证实和推广了先前关于MAPbI3VBM处的强带色散和低DOS的预测。在使用电子能谱来确定卤化铅钙钛矿的前线电子态时，这种低的DOS需要特别注意。
We report valence and conduction band densities of states measured via ultraviolet and inverse photoemission spectroscopies on three metal halide perovskites, specifically methylammonium lead iodide and bromide and cesium lead bromide (MAPbI3, MAPbBr3, CsPbBr3), grown at two different institutions on different substrates. These are compared with theoretical densities of states (DOS) calculated via density functional theory. The qualitative agreement achieved between experiment and theory leads to the identification of valence and conduction band spectral features, and allows a precise determination of the position of the band edges, ionization energy and electron affinity of the materials. The comparison reveals an unusually low DOS at the valence band maximum (VBM) of these compounds, which confirms and generalizes previous predictions of strong band dispersion and low DOS at the MAPbI3 VBM. This low DOS calls for special attention when using electron spectroscopy to determine the frontier electronic states of lead halide perovskites.