Zhang Zixuan, Liang Wenfei, Xue Jie, Li Xin, Wu Kaifeng, Lu Haipeng
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR) 999077, China.
State Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China.
ACS Nano. 2024 Feb 7. doi: 10.1021/acsnano.3c12851.
Magnetic impurity doping in semiconductors has emerged as an important strategy to endow exotic photophysical and magnetic properties. While most reported hosts are centrosymmetric semiconductors, doping magnetic ions into a noncentrosymmetric chiral semiconductor can offer additional control of photonic and spin polarization. In this work, we synthesized a Mn-doped chiral two-dimensional (2D) perovskite, Mn:(-MPA)PbBr (-MPA = -methyl phenethylammonium). We found that the optical activity of chiral 2D perovskites is enhanced with an increased concentration of Mn ions. Additionally, efficient energy transfer from the chiral host to the Mn dopants is observed. This energy transfer process gives rise to circularly polarized luminescence from the excited state of Mn (T → A), exhibiting a photoluminescence quantum yield up to 24% and a dissymmetry factor of 11%. The exciton fine structures of undoped and Mn-doped (-MPA)PbBr are further studied through magnetic circular dichroism (MCD) spectroscopy. Our analysis shows that chiral organic cations lead to an exciton fine structure splitting energy as large as 5.0 meV, and the splitting is further increased upon Mn doping. Our results reveal the strong impacts of molecular chirality and magnetic dopants on the exciton structures of halide perovskites.
半导体中的磁性杂质掺杂已成为赋予奇异光物理和磁性特性的重要策略。虽然大多数报道的主体是中心对称半导体，但将磁性离子掺杂到非中心对称手性半导体中可以提供对光子和自旋极化的额外控制。在这项工作中，我们合成了一种锰掺杂的手性二维（2D）钙钛矿，Mn:(-MPA)PbBr（-MPA = -甲基苯乙铵）。我们发现，随着锰离子浓度的增加，手性二维钙钛矿的光学活性增强。此外，还观察到了从手性主体到锰掺杂剂的高效能量转移。这种能量转移过程导致了锰激发态（T → A）的圆偏振发光，其光致发光量子产率高达24%，不对称因子为11%。通过磁圆二色性（MCD）光谱进一步研究了未掺杂和锰掺杂的(-MPA)PbBr的激子精细结构。我们的分析表明，手性有机阳离子导致激子精细结构分裂能高达5.0 meV，锰掺杂后分裂进一步增加。我们的结果揭示了分子手性和磁性掺杂剂对卤化物钙钛矿激子结构的强烈影响。
