2 research outputs found
Sustained Robust Exciton Emission in Suspended Monolayer WSe_2 within the Low Carrier Density Regime for Quantum Emitter Applications
The development of semiconductor optoelectronic devices is moving toward low power consumption and miniaturization, especially for high-efficiency quantum emitters. However, most of these quantum sources work at low carrier density region, where the Shockley-Read-Hall recombination may dominant and seriously reduce the emission efficiency. In order to diminish the affection of carrier trapping and sustain a strong photoluminescence emission under low power pumping condition, we investigated on the influence of Suspending to monolayered tungsten diselenide, novel two-dimensional quantum material. Not only the PL intensity, but also the fundamental photoluminescence quantum yield has exhibited a huge, order-scale enhancement through suspending, even surprisingly, we found the PLQY improvement revealed far significantly under small pumping power and came out an exponential increase tendency toward even lower carrier density region. With its strong excitonic effect, suspended WSe_2 offers a solution to reduce carrier trapping and participate in non-radiative processes. Moreover, in the low-power range where SRH recombination dominates, suspended WSe_2 exhibited remarkably higher percentage of excitonic radiation compared to contacted WSe_2. Herein, we quantitatively demonstrate the significance of suspended WSe_2 monolayer at low carrier density region, highlighting its potential for developing compact, low-power quantum emitters in the future
Topologically Controlled Cell Differentiation Based on Vapor-Deposited Polymer Coatings
In
addition to the widely adopted method of controlling cell attachment
for cell patterning, pattern formation via cell proliferation and
differentiation is demonstrated using precisely defined interface
chemistry and spatial topology. The interface platform is created
using a maleimide-functionalized parylene coating (maleimide-PPX)
that provides two routes for controlled conjugation accessibility,
including the maleimide–thiol coupling reaction and the thiol–ene
click reaction, with a high reaction specificity under mild conditions.
The coating technology is a prime tool for the immobilization of sensitive
molecules, such as growth factor proteins. Conjugation of fibroblast
growth factor 2 (FGF-2) and bone morphogenetic protein (BMP-2) was
performed on the coating surface by elegantly manipulating the reaction
routes, and confining the conjugation reaction to selected areas was
accomplished using microcontact printing (μCP) and/or UV irradiation
photopatterning. The modified interface provides chemically and topologically
defined signals that are recognized by cultured murine preosteoblast
cells for proliferation (by FGF-2) and osteogenesis (by BMP-2) activities
in specific locations. The reported technique additionally enabled
synergistic pattern formation for both osteogenesis and proliferation
activities on the same interface, which is difficult to perform using
conventional cell attachment patterns. Because of the versatility
of the coating, which can be applied to a wide range of materials
and on curved and complex devices, the proposed technology is extendable
to other prospective biomaterial designs and material interface modifications