文献类型：期刊文献

英文题名：First-Principles Insight into the Degradation Mechanism of CH3NH3PbI3 Perovskite: Light-Induced Defect Formation and Water Dissociation

作者：Peng, Chao[1,2,3];Chen, Jianfu[1,2];Wang, Haifeng[1,2];Hu, P.[1,2,3]

机构：[1]East China Univ Sci & Technol, Ctr Computat Chem, Key Lab Adv Mat, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Sch Chem & Mol Engn, Res Inst Ind Catalysis, Shanghai 200237, Peoples R China;[3]Queens Univ Belfast, Sch Chem & Chem Engn, Belfast BT9 SAG, Antrim, North Ireland

年份：2018

卷号：122

期号：48

起止页码：27340

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY C

收录：;EI(收录号：20184906205065);WOS:【SCI-EXPANDED(收录号:WOS:000452693300025)】；

基金：This project was supported by National Natural Science Foundation of China (21333003, 21622305, and 21873028), National Ten Thousand Talent Program for Young Top-notch Talents in China, the Shanghai "Shu Guang" project (17SG30), and the Fundamental Research Funds for the Central Universities (WJ1616007).

语种：英文

外文关键词：Density functional theory - Layered semiconductors - Lead compounds - Degradation - Perovskite - Dissociation - Perovskite solar cells - Computation theory

摘要：The organic/inorganic hybrid CH3NH3PbI3 perovskite shows promising features in light harvesters, but its instability under humid environment seriously restricts its application. To improve the long-term stability, it is imperative to understand the degradation mechanism at the atomic level. Here, we apply the density functional theory (DFT)+U method to systematically investigate the effect of light and the chemical interaction between the orthorhombic CH3NH3PbI3 (ort-CH3NH3PbI3) and water and some key roles of water/light causing instability of ort-CH3NH3PbI3 are identified. First, we demonstrate that the identified U values (I: 8 eV, Pb: 9 eV) in the DFT+U approach together with spin-orbit coupling can well describe the electronic and basic chemical properties of ortCH(3)NH(3)PbI(3), which is a good balance between the accuracy and computational cost. Second, the photogenerated hole is revealed to thermodynamically promote the formation of surface and bulk iodine vacancies in ort-CH3NH3PbI3(100) system that may induce the hysteresis behavior in current-voltage (J-V) curves and aging of perovskite solar cells. More importantly, the formed defect of iodine vacancy would induce H2O to undergo irreversible dissociation. Third, on the perfect ortCH(3)NH(3)PbI(3)(100) surface in the dark, H2O is found to be difficult to dissociate and incline to molecularly adsorb; in contrast, with a photogenerated electron involved, the dissociation of H2O molecule becomes favorable with a decreased barrier of 0.57 eV. H2O dissociation results in the formation of hydroxyl anion (OH-), which can strongly interact with CH3NH3+ and lead to the formation of CH3NH2, thereby accelerating the ort-CH3NH3PbI3 degradation.