Fig. 4c plots the electronic orbitals of VBM and CBM belonging toeach doping system. From Fig. 4c, we can observe that the electronicorbitals of VBM in different doping systems are similar; however, theCBM shows a big difference. The CBM of the Cu-doped system presentsthe typical d orbitals at Cu atomic positions. The CuI makes a majorcontribution to the CBM in this condition, which can be reflected by thelowest-unoccupied molecular orbitals (LUMO) of [SbCl6]3− and[CuCl6]5− in Fig. 4c. The CBM orbitals of Sb3+/Cu+ co-dopedCs2NaInCl6 show the eg orbitals (dx2− y2 ) of Cu, and Sb3+/Cu2+ codoped Cs2NaInCl6 owns the t2g orbitals (dxz) of Cu. This indicates thatthe Cu ions in the PLE emission process can be more easily excited,contributing to the light emission and corresponding to the yellow lightemission。
Fig. 4b exhibits the normalized projected density of states (DOS) ofnon-doping and doping unit cells with comprised valence bandmaximum (VBM) and conduction band minima (CBM) of the [SbCl6]3−and [CuCl6]5− . In our first-principles simulations, all the doping structures are fully optimized and the lattice parameters’ changes areincluded intrinsically in our theoretical simulations. The local distortions effect is considered both in the modeling the double perovskiteCs2NaInCl6 by Cu+/Sb3+ Co-doping and the emission characteristicstheoretically. The DOS distributions of both Sb-doped and Cu-dopedCs2NaInCl6 are similar, where [CuCl6]5− shows larger CBM–VBM gapthan that of [SbCl6]3− . In Sb/Cu co-doping system, the CBM–VBM gap of[CuCl6]5− can be reduced with increasing Cu feed ratio from 4.96 eV and4.78 eV which means that lower excitation energy for the yellowemission is needed, consistent with our experimental results in Fig. 2b.Surprisingly, the CBM–VBM gap of [SbCl6]3− is 3.78 eV in Sb/Cu codoping Cs2NaInCl6 in Fig. 4b, which is between the split PLE peaks(3.7 and 3.9 eV) and also consistent with our PLE results in Fig. 2b [54].The CBM–VBM gap of [CuCl6]5− is 4.78 eV in Sb/nCu co-dopedCs2NaInCl6, which is also close to the PLE peak (4.5 eV). More specificinformation and electronic band structures of the Cs2NaInCl6 withoutdoping, with Sb ion doping, Cu ion doping, Sb/Cu doping, and Sb/nCudoping are shown in Fig. S9. 作者Author: Lance先生 时间: 2024-6-7 17:20 本帖最后由 Lance先生 于 2024-6-7 17:23 编辑