氯钯共掺对Cs2TiBr6光电性能影响的第一性原理计算

全无机无铅钙钛矿Cs₂TiBr₆具有光电特性良好、带隙可调和环境友好等优点，是一种潜力巨大的光吸收材料。为改善Cs₂TiBr₆的相关性能，我们采用基于第一性原理的方法，针对Pd、Cl掺杂的Cs₂TiBr₆钙钛矿结构进行了研究。结果表明，用Pd取代Ti后产生杂质带，将原来间接带隙的Cs₂TiBr₆转变为直接带隙材料。用25.0% Pd掺杂后，晶体带隙值降低26%，掺杂后的晶体在320~415 nm近紫外光区吸收能力加强约50%，在645~900 nm的红外光区及近红外光区的光吸收能力加强约134%。在此基础上，将Cl与25.0% Pd共掺杂时，Cl掺杂不仅可以把Pd的形成能在单掺的基础上减小约9%，而且Cl的不同掺杂位置对材料的光电性能也有一定的影响。

First Principles Calculation on Photoelectric Properties of Cs2TiBr6 by Substitution Doping with Cl and Pd

The all-inorganic lead-free perovskite Cs₂TiBr₆ has the advantages of good optoelectronic properties, adjustable bandgap, and environmental friendliness. It is a kind of light-absorbing material with great potential. To improve the related properties of Cs₂TiBr₆, the first-principles-based method was used to study the structure of Pd and Cl doped Cs₂TiBr₆ perovskite. The results show that the impurity band was generated after replacing Ti with Pd, which transforms the original indirect bandgap Cs₂TiBr₆ into a direct bandgap material. After doping with 25.0% Pd, the bandgap value of the crystal was reduced by 26%, and the absorption capacity of the doped crystal in the nearultraviolet region of 320-415 nm was enhanced by about 50%. In the infrared and near-infrared regions of 645-900 nm, the light absorption capacity was enhanced by about 134%. On this basis, when Cl was co-doped with 25.0% Pd, Cl doping can reduce the formation energy of Pd by about 9% based on single doping, and the position of Cl doping also affects the photoelectric properties of the material.