High-performance,
monolithic photoactivated gas sensors based on the integration of
gas-sensitive semiconductor metal oxide nanowires on micro light-emitting
diodes (μLEDs) are introduced. The μLEDs showed improved
irradiance and energy conversion efficiency (i.e., external quantum
efficiency, EQE), as the size of LEDs was reduced from 200 ×
200 μm2 (irradiance of 46.5 W/cm2 and
EQE of 4%) to 30 × 30 μm2 (irradiance of 822.4
W/cm2 and EQE of 9%). Gas-sensitive zinc oxide (ZnO) nanowires
were directly synthesized on top of the μLED through a hydrothermal
reaction. The direct contact between the sensing component and μLED
sensor platform leads to high light coupling efficiency, minimizing
power consumption of the sensor. Furthermore, the sensing performance
(i.e., sensitivity) at optimal operating power was improved as the
LED size was reduced. The smallest fabricated gas sensor (active area
= 30 × 30 μm2) showed excellent NO2 sensitivity (ΔR/R
0 = 605% to 1 ppm NO2) at the optimal operating power (∼184
μW). In addition, the sensor showed a low limit of detection
(∼14.9 ppb) and robustness to high humidity conditions, which
demonstrate its potential for practical applications in mobile internet
of things (IoT) devices.
The hybridised resonances between Mie-scatterers and lattice resonances, i.e. quasi-guided mode resonances, are investigated. The scattering of the Mie-resonators is boosted by the first order of transmitted diffracted light which...
Because of its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX 3 (X = I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr 3 polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition rate, which, along with growth temperature, determines the nucleation rate and therefore the eventual grain structure. A correlation between deposition rate and average grain size was noted except for a very large deposition rate when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr 2 films. The growth conditions that produced a nanoscale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr 3 light emitters, we demonstrate a green-light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/ A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr 3 films for high-efficiency LEDs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.