2 research outputs found
Degradation of Two-Dimensional CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Perovskite and CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>/Graphene Heterostructure
Hybrid
organic–inorganic metal halide perovskites have been considered
as promising materials for boosting the performance of photovoltaics
and optoelectronics. Reduced-dimensional condiments and tunable properties
render two-dimensional (2D) perovskite as novel building blocks for
constructing micro-/nanoscale devices in high-performance optoelectronic
applications. However, the stability is still one major obstacle for
long-term practical use. Herein, we provide microscale insights into
the degradation kinetics of 2D CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (MAPbI<sub>3</sub>) perovskite and CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>/graphene heterostructures. It is found that the degradation
is mainly caused by cation evaporation, which consequently affects
the microstructure, light–matter interaction, and the photoluminescence
quantum yield efficiency of the 2D perovskite. Interestingly, the
encapsulation of perovskite by monolayer graphene can largely preserve
the structure of the perovskite nanosheet and maintain reasonable
optical properties upon exposure to high temperature and humidity.
The heterostructure consisting of perovskite and another 2D impermeable
material affords new possibilities to construct high-performance and
stable perovskite-based optoelectronic devices
Infrared Nanoimaging Reveals the Surface Metallic Plasmons in Topological Insulator
Surface plasmons
make a high degree of localization of electromagnetic
fields achievable at the vicinity of metal surfaces. Topological insulators
(TIs) are a family of materials which are insulating in the bulk but
have metallic surfaces caused by the strong spin–orbit coupling.
Surface plasmons supported by the surface state on topological insulators
have attracted incredible interests from ultraviolet to mid-infrared
frequencies. In this work, we experimentally investigate the near-field
properties of Bi<sub>2</sub>Te<sub>3</sub> nanosheets using scattering-type
scanning near-field optical microscopy (s-SNOM). The s-SNOM tip enables
to detect significantly enhanced intensity in its near field at precisely
controlled positions with regards to Bi<sub>2</sub>Te<sub>3</sub> structure.
With the help of highly position-selective excitation and high-pixel
real-space mapping, we discover near-field patterns of bright outside
fringes which are associated with its surface-metallic, plasmonic
behavior at mid-infrared frequency. Thereby, we experimentally demonstrate
that the scattered signal responses and near-field amplitudes of outside
fringes can be tailored via mechanical (sheet thickness of Bi<sub>2</sub>Te<sub>3</sub>), electric (electrostatic gating), and optical
(incident wavelength) fashions. The discovery of outside fringes in
TI nanosheets may enable the development of strongly enhanced light–matter
interactions for quantum optical devices, mid-infrared (MIR) and terahertz
detectors or sensors