Engineering Grain Boundaries in Cu2ZnSnSe4 for Better Cell Performance: A First‐Principle Study
Engineering Grain Boundaries in Cu2ZnSnSe4 for Better Cell Performance: A First‐Principle Study
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DOI：
10.1002/aenm.201300712
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发表时间：
2014
影响因子：
27.8
通讯作者：
W. Yin;Yelong Wu;S. Wei;R. Noufi;M. Al‐Jassim;Yanfa Yan
中科院分区：
文献类型：
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作者：
W. Yin;Yelong Wu;S. Wei;R. Noufi;M. Al‐Jassim;Yanfa Yan
通过第一性原理密度泛函理论（DFT）计算，研究了Cu 2 ZnSnSe 4（CZTSe）中本征和钝化态晶界的原子结构和电子性质. CZTSe中的本征GB在带隙内产生局部深态，从而充当肖克利-里德-霍尔复合中心，这对电池性能是有害的。诸如ZnSn（Sn位点上的Zn原子）、Na+1（间隙Na离子）和OSe（Se位点上的0原子）的缺陷优选在CZTSe中偏析成GB。这些缺陷在GB处的分离表现出两个有益的效果：1）通过错误的键在GB处断裂或弱化来消除深隙态，使得GB电良性;以及2）产生空穴势垒和电子下沉，促进GB处的有效电荷分离。结果表明了一种独特的化学方法，用于在CZTSe中工程化GB以实现改善的电池性能。
Through first‐principle density functional theory (DFT) calculations, the atomic structure and electronic properties of intrinsic and passivated Σ3 (114) grain boundaries (GBs) in Cu2ZnSnSe4 (CZTSe) are studied. Intrinsic GBs in CZTSe create localized deep states within the band gap and thus act as Shockley‐Read‐Hall recombination centers, which are detrimental to cell performance. Defects, such as ZnSn (Zn atoms on Sn sites), Na+i (interstitial Na ions), and OSe (O atoms on Se sites), prefer to segregate into GBs in CZTSe. The segregation of these defects at GBs exhibit two beneficial effects: 1) eliminating the deep gap states via wrong bonds breaking or weakening at GBs, making GBs electrically benign; and 2) creating hole barriers and electron sinkers, promoting effective charge separation at GBs. The results suggest a unique chemical approach for engineering GBs in CZTSe to achieve improved cell performance.