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Photoelectric Sensor News

Data2019-06-03 13:27:23

NRL scientists have found that methods for rejecting optical material defects can miniaturize optoelectronic devices

Scientists at the US Naval Research Laboratory (NRL) have discovered a new way to passivate defects in next-generation optical materials to improve optical quality and miniaturize LEDs and other optical components.

“From a chemical point of view, we have discovered a new photocatalytic reaction that uses lasers and water molecules, which are new and exciting,” said Dr. SaujanSivaram, lead author of the study. “From a general perspective, this work enables the integration of high quality, optically active, atomic thin materials into a variety of applications such as electronics, electrocatalysts, memory and quantum computing applications.”

A laser shot of a water molecule bond at a sulfur vacancy in a single layer of molybdenum disulfide. And photoluminescence (PL) is observed to increase during laser shots in the environment. Shows the bright area and spells "NRL".

NRL scientists have developed a versatile laser processing technology to significantly improve the optical performance of single-layer molybdenum disulfide (MoS2), a straight-gap semiconductor with high spatial resolution. In the area where the laser beam is "written", their process increases the light emission efficiency of the material by a factor of 100.

According to Sivaram's research, transition metal binary (TMD) atomic layers (such as MoS2) are ideal components for flexible devices, solar cells, and photosensors due to their high optical absorption and straight band gap.

“These semiconductor materials are particularly advantageous in applications where weight and flexibility are high,” he said. “Unfortunately, their optical properties are often highly variable and non-uniform, so improving and controlling the optical properties of these TMD materials is The key to achieving reliable, high-efficiency devices."

Sivaram said: "Defects often impair the ability of these single-layer semiconductors to emit light. These defects act as non-radiative trapping states, generating heat rather than light. Therefore, removing or passivating these defects is an important step in achieving high-efficiency optoelectronic devices."In traditional LEDs, approximately 90% of the devices are heat sinks to improve cooling. Reduced defects allow smaller devices to consume less power, making distributed sensors and low-power electronic devices longer to operate.

Researchers have shown that MoS2 is only passivated when water molecules are exposed to laser light with energy above the TMD bandgap. The result is an increase in photoluminescence with no spectral shift.

The treated area remains strongly illuminating compared to the much less untreated area. This table laser drives the chemical reaction between the surrounding gas molecules and MoS2.

“This is an extraordinary achievement,” said Dr. Belen de Junck, senior scientist and lead researcher. “The results of this research paved the way for the use of TMD materials, which are critical to the success of optoelectronic devices and are closely related to the mission of the Department of Defense.”

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