Multiple emissions in a simple hybrid compound with Mn2Cl6 dimer and crowned Pb2+ group revealed by emission decay lifetimes and optomagnetism

Abstract

Lead halide hybrids are outstanding and promising optoelectronic materials, and doping Mn2+ is a feasible and effective strategy for modulating its optoelectronic properties via electrostatic or spin interaction. Yet, the photoluminescence (PL) mechanisms like whether excitons, self-trapped excitons (STEs) emission or 6p-6s transition of Pb2+, and whether isolated Mn2+ or spin-coupled Mn2+-Mn2+ pairs contributes to the PL, etc., remain largely uncertain. The heterometallic complex [Pb(C12H24O6)Cl]2[Mn2Cl6] (PMC) composed of [Pb(C12H24O6)Cl]+ cations and Mn2Cl6 dimers serves as an ideal model for investigating the interplay between spins and charge carriers. Multiple emissions originated from the 6p-6s transition of Pb2+ (λex=276 nm, λem=437 nm, τ180 K=9.13 ns), d-d transition of Mn2+ ion (λex=363 nm, λem=557 nm, τ300 K=0.6363 ms), d-d transition of spin-coupled Mn2+-Mn2+ dimers (λex=276 nm, λem=676 nm, τ300 K=0.7210 ms) and STEs of crowned Pb2+ group (λex=305 nm, λem=588 nm, τ300 K=0.0265 ms) could be roughly identified via excitation-wavelength-dependent/temperature-dependent PL spectra and decay lifetimes as well as photoinduced electron spin resonance spectra and magnetic measurements, though the latter three are apparently overlapped. This study reveals the PL behaviors of PMC concerning localized centers of Mn2+/Pb2+ and delocalized Mn2Cl6 dimers/crowned Pb2+ group, manifesting a complex photoexcitation and PL mechanism in those lead halides with manganese.