Team develops laser processing method to increase efficiency of optoelectronic devices


(Leading) Illustration of a water particle bonding at a sulfur job in the MoS2 upon laser light direct exposure. (Bottom) Photoluminescence (PL) increase observed throughout laser light direct exposure in ambient. (Inset) Fluorescence image revealing lightened up areas defining ‘NRL.’ Credit: U.S. Naval Lab

Researchers at the U.S. Naval Lab (NRL) found a brand-new method to passivate flaws in next generation optical products to enhance optical quality and make it possible for the miniaturization of light discharging diodes and other optical aspects.


“From a chemistry standpoint, we have discovered a new photocatalytic reaction using laser light and water molecules, which is new and exciting,” stated Saujan Sivaram, Ph.D., lead author of the research study. “From a general perspective, this work enables the integration of high quality, optically active, atomically thin material in a variety of applications, such as electronics, electro-catalysts, memory, and quantum computing applications.”

The NRL researchers established a flexible laser processing strategy to substantially enhance the optical residential or commercial properties of monolayer molybdenum disulphide (MoS2)—a direct space semiconductor—with high spatial resolution. Their procedure produces a 100-fold increase in the product’s optical emission efficiency in the locations “written” with the laser beam.

According to Sivaram, atomically thin layers of shift metal dichalcogenides (TMDs), such as MoS2, are appealing elements for versatile devices, solar batteries, and optoelectronic sensing units due to their high optical absorption and direct band space.

“These semiconducting materials are particularly advantageous in applications where weight and flexibility are a premium,” he stated. “Unfortunately, their optical properties are often highly variable and non-uniform making it critical to improve and control the optical properties of these TMD materials to realize reliable high efficiency devices.”

“Defects are often detrimental to the ability of these monolayer semiconductors to emit light,” Sivaram stated. “These defects act as non-radiative trap states, producing heat instead of light, therefore, removing or passivating these defects is an important step towards high efficiency optoelectronic devices.”

In a standard LED, roughly 90 percent of the gadget is a heat sink to enhance cooling. Lowered flaws make it possible for smaller sized devices to take in less power, which leads to a longer functional life time for dispersed sensing units and low-power electronic devices.

The scientists showed that water particles passivate the MoS2 just when exposed to laser light with an energy above the band space of the TMD. The outcome is an increase in photoluminescence without any spectral shift.

Dealt with areas preserve a strong light emission compared to the without treatment areas that show much a weaker emission. This recommend that the laser light drives a chain reaction in between the ambient gas particles and the MoS2.

“This is a remarkable achievement,” stated Berend Jonker, Ph.D., senior researcher and primary detective. “The results of this study pave the way for the use of TMD materials critical to the success of optoelectronic devices and relevant to the Department of Defense mission.”


Researchers establish a nanometer-scale light bulb from monolayer MoS2


More info:
Saujan V. Sivaram et al, Spatially Selective Improvement of Photoluminescence in MoS2 by Exciton-Mediated Adsorption and Flaw Passivation, ACS Applied Products & Interfaces (2019). DOI: 10.1021/acsami.9b00390

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Team develops laser processing method to increase efficiency of optoelectronic devices (2019, April 15)
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