Photoluminescence Temperature Dependence, Dynamics, and Quantum Efficiencies in Mn2+-Doped CsPbCl3 Perovskite Nanocrystals with Varied Dopant Concentration

4 years ago

Photoluminescence Temperature Dependence, Dynamics, and Quantum Efficiencies in Mn2+-Doped CsPbCl3 Perovskite Nanocrystals with Varied Dopant Concentration

Daniel R. Gamelin, Jialong Zhao, Yunjun Wang, Sihang Ji, Haibo Li, Zhao Zhao, Xi Yuan, Michael C. De Siena, Liling Fei

A series of Mn²⁺-doped CsPbCl₃ nanocrystals (NCs) was synthesized using reaction temperature and precursor concentration to tune Mn²⁺ concentrations up to 14%, and then studied using variable-temperature photoluminescence (PL) spectroscopy. All doped NCs show Mn²⁺ ⁴T_1g → ⁶A_1g d–d luminescence within the optical gap coexisting with excitonic luminescence at the NC absorption edge. Room-temperature Mn²⁺ PL quantum yields increase with increased doping, reaching ∼60% at ∼3 ± 1% Mn²⁺ before decreasing at higher concentrations. The low-doping regime is characterized by single-exponential PL decay with a concentration-independent lifetime of 1.8 ms, reflecting efficient luminescence of isolated Mn²⁺. At elevated doping, the decay is shorter, multiexponential, and concentration-dependent, reflecting the introduction of Mn²⁺–Mn²⁺ dimers and energy migration to traps. A large, anomalous decrease in Mn²⁺ PL intensity is observed with decreasing temperature, stemming from the strongly temperature-dependent exciton lifetime and slow exciton-to-Mn²⁺ energy transfer, which combine to give a strongly temperature-dependent branching ratio for Mn²⁺ sensitization.

Publisher URL: http://dx.doi.org/10.1021/acs.chemmater.7b03311

DOI: 10.1021/acs.chemmater.7b03311