He Yuan,Shilin Jin,Song Zheng,Rong Xie,Tao Pang,Bin Zhuang,Feng Huang,Daqin Chen
In the last five years, significant progress has been achieved in incorporating trivalent lanthanide (Ln3+) ions into CsPbX3 halide perovskite nanocrystals (PeNCs), combining superior optoelectronic performance of semiconductors with abundant Ln3+: 4f–4f transitions. However, doping divalent europium (Eu2+) with parity-allowed 5d–4f transition inside CsPbX3 remains unexplored. Herein, we develop a new class of dual-emitters based on Eu2+-doped CsPbCl3 PeNCs. Narrowband violet emission and broadband orange emission assigned to the respective exciton recombination and Eu2+: 5d → 4f transition are concurrently observed. Steady/transient-state photoluminescence (PL) spectra, time-resolved PL (TRPL) spectra and femtosecond transient absorption (fs-TA) spectra evidence independent dual-emissions without exciton-to-Eu2+ energy transfer, which is attributed to the preferred location of Eu2+ on the surface of CsPbCl3. As a consequence, exciton-longitudinal optical phonon interplay and surface ligand–Eu2+ coupling in the as-prepared Eu:CsPbCl3 PeNCs are verified based on temperature-sensitive spectroscopic analyses, together with first-principles density functional theory (DFT) calculations and crystal-field calculations. These findings provide fundamental insights into the design of novel lanthanide-doped halide perovskite emitters for versatile optoelectronic applications.
Li Guowei,Jiang Shihui,Liu Aijun,Ye Lixiang,Ke Jianxi,Liu Caiping,Chen Lian,Liu Yongsheng,Hong Maochun
Crystal-field perturbation is theoretically the most direct and effective method of achieving highly efficient photoluminescence from trivalent lanthanide (Ln 3+ ) ions through breaking the parity-forbidden nature of their 4 f -transitions. However, exerting such crystal-field perturbation remains an arduous task even in well-developed Ln 3+ -doped luminescent nanocrystals (NCs). Herein, we report crystal-field perturbation through interstitial H + -doping in orthorhombic-phase NaMgF 3 :Ln 3+ NCs and achieve a three-orders-of-magnitude emission amplification without a distinct lattice distortion. Mechanistic studies reveal that the interstitial H + ions perturb the local charge density distribution, leading to anisotropic polarization of the F − ligand, which affects the highly symmetric Ln 3+ -substituted [MgF 6 ] 4− octahedral clusters. This effectively alleviates the parity-forbidden selective rule to enhance the 4 f –4 f radiative transition rate of the Ln 3+ emitter and is directly corroborated by the apparent shortening of the radiative recombination lifetime. The interstitially H + -doped NaMgF 3 :Yb/Er NCs are successfully used as bioimaging agents for real-time vascular imaging. These findings provide concrete evidence for crystal-field perturbation effects and promote the design of Ln 3+ -doped luminescent NCs with high brightness.
危险品化学品经营许可证（带存储）