Du Mao-Hua
J Phys Chem Lett. 2015 Apr 16;6(8):1461-6. doi: 10.1021/acs.jpclett.5b00199. Epub 2015 Apr 3.
Native point defects play an important role in carrier transport properties of CH3NH3PbI3. However, the nature of many important defects remains controversial due partly to the conflicting results reported by recent density functional theory (DFT) calculations. In this Letter, we show that self-interaction error and the neglect of spin-orbit coupling (SOC) in many previous DFT calculations resulted in incorrect positions of valence and conduction band edges, although their difference, which is the band gap, is in good agreement with the experimental value. This problem has led to incorrect predictions of defect-level positions. Hybrid density functional calculations, which partially correct the self-interaction error and include the SOC, show that, among native point defects (including vacancies, interstitials, and antisites), only the iodine vacancy and its complexes induce deep electron and hole trapping levels inside of the band gap, acting as nonradiative recombination centers.
本征点缺陷在CH3NH3PbI3的载流子输运特性中起着重要作用。然而，许多重要缺陷的性质仍存在争议，部分原因是近期密度泛函理论（DFT）计算报告的结果相互矛盾。在本信函中，我们表明，许多先前的DFT计算中自相互作用误差和自旋轨道耦合（SOC）的忽略导致了价带和导带边缘位置的不正确，尽管它们的差值（即带隙）与实验值吻合良好。这个问题导致了缺陷能级位置的错误预测。混合密度泛函计算部分校正了自相互作用误差并包含了SOC，结果表明，在本征点缺陷（包括空位、间隙原子和反位缺陷）中，只有碘空位及其复合物在带隙内诱导出深电子和空穴俘获能级，充当非辐射复合中心。
