Restricting the Formation of Pb-Pb Dimer via Surface Pb Site Passivation for Enhancing the Light Stability of Perovskite.
Restricting the Formation of Pb-Pb Dimer via Surface Pb Site Passivation for Enhancing the Light Stability of Perovskite.
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DOI：
10.1002/smll.202201831
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发表时间：
2022-05
期刊：
影响因子：
13.3
通讯作者：
X. Feng;Biao Liu;Yongyi Peng;Chenxi Gu;X. Bai;Mengqiu Long;M. Cai;Chuanjia Tong;Liyuan Han;Jun-liang Yang
中科院分区：
文献类型：
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作者：
X. Feng;Biao Liu;Yongyi Peng;Chenxi Gu;X. Bai;Mengqiu Long;M. Cai;Chuanjia Tong;Liyuan Han;Jun-liang Yang
光稳定性差阻碍了钙钛矿光电器件的潜在应用。最近的实验表明，通过形成强化学键（SO 4-Pb，PO 4-Pb，Cl-Pb，O-Pb和S-Pb）的钝化表面可以有效地提高钙钛矿太阳能电池的光稳定性。然而，根本原因尚不清楚。在这里，难以捉摸的光稳定性增强的基本机制进行了详细解释，使用第一性原理计算。小极化子模型和自陷激子模型表明，在光照下，钙钛矿表面的碘空位缺陷可以捕获自由电子，导致Pb-I晶格的显著重排，并产生新的化学物种，Pb-Pb二聚体结合在CH 3 NH3 PbI 3的典型钙钛矿中。Pb-Pb二聚体使Pb-I八面体晶格发生畸变，降低了I原子的缺陷形成能。表面Pb位钝化可以防止Pb-Pb二聚体的形成，从而提高光稳定性。此外，强离子键可以更好地稳定Pb位。本研究对钙钛矿光稳定性和钝化机理的深入理解，将促进钙钛矿光电器件的应用。
Poor light stability hinders the potential applications of perovskite optoelectronic devices. Recent experiments have demonstrated that the passivation surface via forming strong chemical bonds (SO4 -Pb, PO4 -Pb, Cl-Pb, O-Pb, and S-Pb) could effectively improve the light stability of perovskite solar cells. However, the underlying reasons are not clear. Herein, the elusive underlying mechanisms of light stability enhancement are explained in detail using first principles calculations. The small polaron model and self-trapped exciton model demonstrate that an iodine vacancy defect on the surface of perovskite could trap a free electron under light illumination, which leads to a significant rearrangement of the Pb-I lattice and creats a new chemical species, i.e., a Pb-Pb dimer bound in the typical perovskite of CH3 NH3 PbI3 . The Pb-Pb dimer distorts the Pb-I octahedral lattice and reduces the defect formation energy of the I atoms. The surface Pb site passivation can prevent the formation of the Pb-Pb dimer, thereby improving the light stability. In addition, the strong ionic bond could better stabilize the Pb site. The in-depth understanding of the light stability and the passivation mechanism in this study can promote the application of perovskite optoelectronic devices.