No abstract

In this work, we develop an environmental-friendly approach to produce organic-inorganic hybrid MAPbBr3 (MA = CH3NH3) perovskite nanocrystals (PeNCs) and PMMA-MAPbBr3 NC films with excellent compression-resistant PL characteristics. Deionized water is used as the solvent to synthesize MAPbBr3 powder instead of conventionally-used hazardous organic solvents. The MAPbBr3 PeNCs derived from the MAPbBr3 powder exhibit a high photoluminescence quantum yield (PLQY) of 93.86%. Poly(methyl methacrylate) (PMMA)-MAPbBr3 NC films made from the MAPbBr3 PeNCs retain ~97% and ~91% of initial PL intensity after 720 h aging in ambient environment at 50 °C and 70 °C, respectively. The PMMA-MAPbBr3 NC films also exhibit compression-resistant photoluminescent characteristics in contrast to the PMMA-CsPbBr3 NC films under a compressive stress of 1.6 MPa. The PMMA-MAPbBr3 NC film integrated with a red emissive film and a blue light emitting source achieves an LCD backlight of ~114% color gamut of National Television System Committee (NTSC) 1953 standard.

Thiol containing molecules as both interfacial surface ligands and additives are promising modulators for enhancing photoluminescence (PL) properties, stability, and photovoltaic (PV) performance of metal halide perovskites. However, alkanethiols are much more effective for improving photoluminescence (PL) intensity and stability in metal halide perovskite nanocrystals than in their thin film analogues. Herein, we investigate how additional functional groups on a pyrimidine core can alter thiol reactivity and influence the PL, stability, and PV performance of organic metal halide perovskites. Through an investigation of five different pyrimidine derivatives, it is shown that all derivatives containing thiol groups form thiolates in the presence of the perovskite precursors and increase the photoluminescence intensity of the perovskite film. The largest all-around improvement to the PL intensity, stability, and photovoltaic performance of Cs 0.15 FA 0.85 PbI 3 perovskites is realized through the addition of a hydroxyl group combined with a trifluoromethyl group to form 4-hydroxy-6-(trifluoromethyl)pyrimidine-2-thiol. This investigation helps illuminate how combinations of functional groups can be employed to further increase the beneficial effects over monofunctional additives in organic metal halide perovskites.

Carbon dots (C-dots) are a promising class of carbonaceous nanomaterials for bioimaging, catalysis, and optoelectronics. However, their applications are alarmed by recent reports that bright molecular fluorophores are co-produced in...

Graphene layers placed on SrTiO3 single-crystal substrates, i.e., templates for remote epitaxy of functional oxide membranes, were investigated using temperature-dependent confocal Raman spectroscopy. This approach successfully resolved distinct Raman modes of graphene that are often untraceable in conventional measurements with non-confocal optics due to the strong Raman scattering background of SrTiO3. Information on defects and strain states was obtained for a few graphene/SrTiO3 samples that were synthesized by different techniques. This confocal Raman spectroscopic approach can shed light on the investigation of not only this graphene/SrTiO3 system but also various two-dimensional layered materials whose Raman modes interfere with their substrates.