Manganese doped inorganic halide perovskites continue to be of current interest for applications in light emitting devices and down-converters in solar cells. In this work we prepared Mn doped CsPbCl3 (Mn: CPC) bulk crystals and nano-particles (NPs) and compared their emission properties. Bulk crystals were grown from the melt by vertical Bridgman technique and NPs were synthesized using a microwave assisted method. Under ultraviolet excitation at 350 nm, bulk crystal and NPs exhibited a broad orange emission centered in the ~600 nm range at room temperature. The broadband emission was assigned to the intra-3d transition 4T1 → 6A1 of Mn2+ ions incorporated in the CPC host lattice. The Mn2+ emission lifetimes were nearly exponential with values of 1.1 ms for NPs and 0.7 ms for the bulk crystal. NPs also showed exciton emission peaking at ~402 nm, whereas the bulk crystal exhibited no emission near the band-edge. Instead, the bulk material revealed a weak below-gap emission in the 450-550 nm region suggesting the existence of defect states. The excitation spectra for the orange Mn2+ emission from NPs and bulk crystals of Mn: CPC were significantly different indicating distinct excitation pathways. The excitation spectrum of the orange Mn2+ emission from NPs showed excitonic structure similar to the absorption spectrum suggesting an efficient energy transfer from excitons to Mn2+ ions. In contrast, UV excitation was less efficient for the bulk crystal and the excitation was dominated by below-gap excitation bands centered at 427 and 500 nm.
Spectroscopic characteristics of the lower lying energy levels of Pr3+ doped into the low-phonon energy hosts CsPbCl3 and TlPb2Br5 were explored for mid-IR laser applications. Both crystals posses relatively large IR absorption cross-sections for their 3F4+3F3 and 3F2+3H6 excited states, which indicates efficient optical pumping at either ~1.5 µm and ~2.0 µm, respectively. Pr: TlPb2Br5 exhibited an efficient MIR emission at room temperature with a lifetime of ~37 ms making it a promising candidate for laser applications. Only weak MIR emission was observed from Pr: CsPbCl3 due to strong emission quenching. More details of the IR spectroscopy including temperature dependent spectral and lifetime studies will be presented at the conference.
Recently, a novel optical technology, LIBS in mid-IR (MWIR/LWIR) region was developed to capture the infrared molecular emission signatures from those vibrationally excited intact sample molecules excited by laser-induced plasma. Mid-IR LIBS is the first mid-IR emission spectroscopy that can complement LIBS and Raman as rapid, in situ, and standoff chemical characterization probes without the need of any sample preparation. With all the advantages of the conventional UVN LIBS, the UVN + LWIR LIBS spectrometer can rapidly and unambiguously reveal both the elemental composition and molecular makeups of the sample that is meters away without any sample preparation required and without the need to unscramble the spectral fingerprints of targets from the irregular and cluttered background. UVN + LWIR LIBS is able to provide in-situ, real-time/near-real-time chemical detection and identification regardless of the shapes and conditions of the sample surface while requiring no need for any sample preparations. One does not need to do anything to the target sample, just point the laser at the intended target and get the spectral signatures back within a millisecond.
We report on the materials development and infrared (IR) optical spectroscopy of Dy3+-doped into the ternary lead halides compounds TlPb2Br5 and CsPbCl3 for photonic applications. The investigated Dy-doped ternary lead halides were synthesized from purified starting materials followed by melt-growth using vertical Bridgman technique. Under optical pumping at 1.35 μm (6H15/2→6H 9/2+6F11/2), broad mid-IR emissions in the ~2.9 μm (6H13/2→6H15/2), ~4.3 μm (6H11/2→6H 13/2), and ~5.4 μm (6H9/2 +6F11/2 →6H15/2) regions were observed at room-temperature. Compared to Dy: TlPb2Br5, the mid-IR emission from Dy: CsPbCl3 was significantly weaker suggesting the existence of non-radiative losses. Temperature dependent lifetime studies and a Judd-Ofelt analysis were performed for Dy: TlPb2Br5.
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