A metal-organic hybrid perovskite (CH3NH3PbI3) with three-dimensional framework of metal-halide octahedra has been reported as a low-cost, solution-processable absorber for a thin-film solar cell with a power-conversion efficiency over 20%. Low-dimensional layered perovskites with metal halide slabs separated by the insulating organic layers are reported to show higher stability, but the efficiencies of the solar cells are limited by the confinement of excitons. In order to explore the confinement and transport of excitons in zero-dimensional metal–organic hybrid materials, a highly orientated film of (CH3NH3)3Bi2I9 with nanometre-sized core clusters of Bi2I9
3− surrounded by insulating CH3NH3
+ was prepared via solution processing. The (CH3NH3)3Bi2I9 film shows highly anisotropic photoluminescence emission and excitation due to the large proportion of localised excitons coupled with delocalised excitons from intercluster energy transfer. The abrupt increase in photoluminescence quantum yield at excitation energy above twice band gap could indicate a quantum cutting due to the low dimensionality.
Atmospheric pressure plasmas (APPs) have achieved great scientific and technological advances for a wide range of applications. The synthesis and treatment of materials by APPs have always attracted great attention due to potential economic benefits if compared to low-pressure plasma processes. Nonetheless, APPs present very distinctive features that suggest atmospheric pressure operation could bring other benefits for emerging new technologies. In particular, materials synthesized by APPs which are suitable candidates for third generation photovoltaics are reviewed here.
This paper reports the production of strongly confined ligand-free, defect-free, hydroxy-terminated ZnO quantum dots with a mean diameter of 1.9 nm, by radio frequency atmospheric pressure microplasma. Systematic characterization is performed to understand the surface chemistry of ZnO quantum dots. Photoluminescence studies show strong confinement effect on emission with only ultraviolet (UV) emission without any defect-related visible emission. Emission is again tested after eighteen months and confirms the QDs long-term emission stability. The mechanism responsible for this UV emission is also discussed and originates from OH-related surface terminations.
Porous ZnO nanocrystalline films have drawn research attention due to improvement in gas sensing, adsorption, photocatalytic, and photovoltaic applications. However, scalable synthesis of porous nanostructures has been a challenge. Here, This paper reports a very easy, fast, and scalable one‐step process for synthesis and deposition of porous ZnO nanocrystalline film by low‐temperature atmospheric pressure plasma. The plasma is generated with radio frequency power using a metallic zinc wire as a precursor. Nanostructures have been synthesized and agglomerate to form a porous film at the substrate. Energy band structure of the deposited film has been investigated to understand the corresponding band alignment, which is relevant to many applications. An in‐depth study of the grown nanostructured ZnO film has been included and characterized by X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy, kelvin probe measurement, ultra‐violet/visible absorption, and photoluminescence.
This paper describes one-pot solution combustion synthesis of La2–x
Sb
x
O3 (0.02 ≤ x ≤ 0.10). Detailed
characterization using X-ray diffraction (XRD) and X- ray photoelecron
spectroscopy (XPS) is carried out to understand the doping effect
and the oxidation state of antimony. Further, temperature-programmed
desorption (TPD) with CO2 is performed for evaluating the
basic property and temperature-programmed reduction (TPR) with H2 has been employed to obtain the oxygen storage capacity.
The comparative study of La2O3, La2–x
Sb
x
O3 (0.02
≤ x ≤ 0.10) shows that as the concentration
of Sb increases, the basicity decreases and the oxygen storage capacity
increases. Thus, nonreducible and basic La2O3 can be transformed to significantly reducible and acidic La2–x
Sb
x
O3 (0.02 ≤ x ≤ 0.10). Further,
solid state UV spectroscopy shows that due to the antimony doping,
band gap of La2O3 decreases significantly. Moreover,
antimony doping also modifies the support property of La2O3 as demonstrated in the catalytic CO2 methanation
reaction in the presence of hydrogen. Ru-doped La2O3 and La1.96Sb0.04O3 shows
different selectivity toward methane formation and the later favors
the reverse water gas shift reaction.
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