Doping is an effective strategy for tailoring the optical properties of 0D Cs 4 PbX 6 (X = Cl, Br, and I) perovskite nanocrystals (NCs) and expanding their applications. Herein, a unique approach is reported for the controlled synthesis of pure-phase Mn 2+ -doped Cs 4 PbCl 6 perovskite NCs and the excited-state dynamics of Mn 2+ is unveiled through temperature-dependent steady-state and transient photoluminescence (PL) spectroscopy. Because of the spatially confined 0D structure of Cs 4 PbCl 6 perovskite, the NCs exhibit drastically different PL properties of Mn 2+ in comparison with their 3D CsPbCl 3 analogues, including significantly improved PL quantum yield in solid form (25.8%), unusually long PL lifetime (26.2 ms), large exciton binding energy, strong electron–phonon coupling strength, and an anomalous temperature evolution of Mn 2+ -PL decay from a dominant slow decay (in tens of ms scale) at 300 K to a fast decay (in 1 ms scale) at 10 K. These findings provide fundamental insights into the excited-state dynamics of Mn 2+ in 0D Cs 4 PbCl 6 NCs, thus laying a foundation for future design of 0D perovskite NCs through metal ion doping toward versatile applications.
Peng Chen,Keke Hu,Xinyu Lin,Zhongliao Wang,Yumeng Zhang,Qinzhuang Liu,Zhongliang Liu
Zero-dimensional metal halide perovskites with strong self-trapped exciton (STE) emission are promising for efficient lighting and sensing, but STE → dopant energy transfer is not well quantified. Here we use Sb 3+ -doped Cs 4 PbCl 6 nanocrystals as a model and combine temperature-dependent steady-state and time-resolved photoluminescence, rate-equation analysis and first-principles calculations to clarify the STE → Sb 3+ cascade sensitization. Emission and excitation spectra confirm successful Sb incorporation. The 360 nm ultraviolet band is assigned to STE recombination, whereas the green band originates from STE → Sb 3+ transfer and the Sb 3+ 3 P 1 → 1 S 0 transition. The transfer efficiency (∼64 %) shows that STE feeding dominates the excitation of Sb centers. Low-temperature PL analysis reveals distinct electron–phonon coupling: STE emission couples mainly to low-frequency phonons, while Sb 3+ emission couples more strongly to high-frequency modes. The extracted activation energies and the cooperative increase of τ STE and τ Sb with decreasing temperature support a thermodynamically downhill STE → Sb 3+ migration. Within a rate-equation framework, the rise time of Sb 3+ emission satisfies t rise ≈ τ STE and yields a characteristic cascade-like transient profile. Density-functional calculations indicate Sb-5p acceptor levels inside the bandgap, providing an energetic basis for localized STE → Sb 3+ coupling and design guidelines for efficient 0D perovskite emitters.
Doping cesium lead halide perovskite nanocrystals (NCs) with Mn 2+ brings attractive long-wavelength emission and flexible color tunability. However, due to multiple competing factors, the exciton-to-Mn 2+ energy transfer efficiency is low. In this work, a simple structure-optimization strategy is applied to enhance the exciton-to-Mn 2+ energy transfer by synthesizing Mn 2+ activated 3D/0D Cs–Pb–Cl perovskite composition composed of 3D CsPbCl 3 and 0D Cs 4 PbCl 6 NCs. The results reveal that the energy transfer efficiency and the photoluminescence quantum efficiency of the Cs–Pb–Cl composite are 65.3% and 77.3%, respectively, which are 1.4 and 3 times the corresponding values of the single-phase CsPbCl 3 :Mn 2+ NCs. Based on the detailed experimental and calculation results, the performance enhancement is demonstrated to stem from the optimized growth process of 3D CsPbCl 3 NCs when co-generating with 0D Cs 4 PbCl 6 NCs. The strong lattice rigidity of the optimized CsPbCl 3 NCs suppresses the nonradiative combination rate of the excitons, thus alleviating the main competing factor of the energy transfer process and improving the energy transfer efficiency. Fabrication of a white light-emitting diode prototype further illustrates the application potential of the orange-emitting Cs–Pb–Cl composite NCs for general lighting.
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