Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation
Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation
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DOI：
10.1039/d0ma00994f
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发表时间：
2021-03
期刊：
影响因子：
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通讯作者：
A. Suzuki;T. Oku
中科院分区：
文献类型：
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作者：
A. Suzuki;T. Oku
用第一性原理计算方法研究了掺Eu的CH(NH2)2PbI3(FAPbI3)和CH3NH3PbI3(MAPbI3)钙钛矿晶体的混合价态对电子结构的影响。Eu离子在钙钛矿晶体中的部分取代影响了与载流子迁移率相关的电子结构和有效质量。在FAPb(Eu+3)I3晶体中，碘的5P轨道分布在价带附近，Eu3+离子的3d轨道分布在导带附近。Eu~(3+)离子的掺入使晶体的有效质量比(Me~*/Me，Mh~*/Me)略有增加，提供了价带附近较宽的3d，4f-5p杂化轨道的分布，影响了能带色散，降低了Me~*/Me和Mh~*/Me，有望改善载流子迁移率。MAPB(Eu~(2+))I_3晶体的~(127)I-核磁共振谱的化学位移为各向同性。~(157)Eu-核磁共振和g-张量的化学位移依赖于配位结构中基于电场梯度和不对称参数的四极相互作用。基于Eu2+-I带3d，4f-5p轨道杂化的电子关联促进了载流子的行程，这有望改善与短路电流密度和转换效率相关的载流子迁移率，从而提高光伏性能。
Effects of mixed-valence states of europium (Eu)-incorporated CH(NH2)2PbI3 (FAPbI3) and CH3NH3PbI3 (MAPbI3) perovskite crystals on electronic structures were investigated by first-principles calculation. Partial replacements of europium ions into the perovskite crystal influenced the electronic structures and the effective mass related to carrier mobility. In the case of the FAPb(Eu+3)I3 crystal, there was wide distribution of the 5p orbital of iodine near the valence band, and the 3d orbital of the Eu3+ ion near the conductive band. The incorporation of Eu3+ ion into the crystal slightly caused to increase the effective mass ratio (me*/me, mh*/me) as compared with those of the FAPbI3 crystal, provided the wide distribution of 3d, 4f-5p hybrid orbitals near the valence band, and influenced the band dispersion with a decrease of me*/me and mh*/me, which is expected for improving the carrier mobility. The chemical shifts of 127I-NMR of the MAPb(Eu2+)I3 crystal indicated isotropic behavior. The chemical shifts of 157Eu-NMR and g-tensor depended on the quadrupole interaction based on the electron field gradient and asymmetry parameter in the coordination structure. The electronic correlation based on hybrization of the 3d, 4f-5p orbital in the Eu2+-iodine band promoted the carrier itinerary, which was expected to improve the carrier mobility related to the short circuit current density and the conversion efficiency as the photovoltaic performance.