一价铜离子掺杂无铅钙钛矿Cs_(2)AgBiBr_(6)对晶体结构和电学性能影响第一性原理模拟研究

First-principles simulation study on the impact of monovalent Cu ion doping on the crystal structure and electrical properties of lead-free perovskite Cs_(2)AgBiBr_(6)

无铅双钙钛矿Cs_(2)AgBiBr_(6)作为环境友好型材料受到了核辐射探测领域的广泛关注,实验上发现对Cs_(2)AgBiBr_(6)进行Cu^(+)掺杂能够显著提高材料稳定性与光电转换率。目前Cu^(+)掺杂Cs_(2)AgBiBr_(6)的影响还未得到理论系统研究,本文基于第一性原理,采用密度泛函,开展了Cu^(+)掺杂Cs_(2)AgBiBr_(6)对结构和电学性能影响的模拟研究。研究结果表明,Cu^(+)掺杂会提高Cs_(2)AgBiBr_(6)的稳定性。掺杂形成的Cs_(2)Ag_(1-x)Cu_(x)BiBr_(6)与原始材料Cs_(2)AgBiBr_(6)皆为间接带隙半导体,并随着Cu^(+)掺杂比例提高能带间隙会显著缩短。根据态密度图分析,能带间隙缩短是由于Cu^(+)掺杂会导致由Bi6p轨道主导的导带底部下移。Cs_(2)Ag_(1-x)Cu_(x)BiBr_(6)相比Cs_(2)AgBiBr_(6)具有更高的稳定性与更优的电学性能,可作为半导体辐射探测器的候选材料。

[Background]Lead-free double perovskite Cs_(2)AgBiBr_(6) has garnered significant attention in the field of nuclear radiation detection as an environmentally friendly material.Experimental observations have revealed that doping Cs_(2)AgBiBr_(6) with Cu^(+)significantly enhances the material's stability and photoelectric conversion efficiency.[Purpose]This study aims to investigate the impact of Cu^(+)doping on the crystal structure and electrical properties of Cs_(2)AgBiBr_(6).[Methods]Based on density functional theory,first-principles calculations were applied to exploring the effects of Cu^(+)doping on the structure and electrical properties of Cs_(2)AgBiBr_(6).Structural properties,such as the stability,doping formation energy,lattice parameters,elastic constants,of Cu^(+)doping on the lead-free double perovskite Cs_(2)AgBiBr_(6) were investigated by simulation whilst the band analysis and density of states analysis were employed to study the impact of electrical performance.[Results]The results indicate that Cu^(+)doping enhances the stability of Cs_(2)AgBiBr_(6).The Cs_(2)Ag_(1-x)Cu_(x)BiBr_(6) compounds formed by doping,as well as the original Cs_(2)AgBiBr_(6) material,exhibit indirect bandgap semiconductor behavior.The bandgap significantly narrows with an increase in the Cu^(+)doping ratio.Based on an analysis of the density of states(DOS),the bandgap narrowing can be attributed to the downward shift of the conduction band minimum dominated by Bi6p orbitals due to Cu^(+)doping.[Conclusions]Cs_(2)Ag_(1-x)Cu_(x)BiBr_(6) exhibits greater stability and superior electrical properties compared to Cs_(2)AgBiBr_(6),making it a promising candidate material for semiconductor radiation detectors.