American scientists have discovered for the first time that light can be captured and manipulated at a wavelength of around 400nm.

It is reported that the U.S. Department of Energy's Ames Laboratory has successfully developed a near-ultraviolet all-organic light-emitting diode (OLED) that can be used as an on-chip photosensitive device. It is reported that this is the first time that scientists have discovered that light can be captured and manipulated near the end of the invisible spectrum with a wavelength of around 400nm.

"Our ideal goal is to create a small chip that can host an entire spectrometer that can be used to measure the spectrum of anything that absorbs or emits light," said Ames Laboratory scientist Joseph Shinar. "This invention is a step in that direction."

Although scientists are very interested in visible OLEDs replacing traditional LEDs and being widely used in consumer electronics, they have done little research on OLEDs in the ultraviolet spectrum range. "This has also led to a decrease in demand for small, flexible devices in analytical applications," explains Ruth Shinar, a scientist at Ames Laboratory in conjunction with the Iowa State University Microelectronics Research Center.

She added: "These devices can be used in areas such as food safety, water quality, medical diagnostics and biosensing. They are portable, affordable and easy to handle."

In addition, the researchers explored the impact of optical microcavities. Optical microcavities are structures formed by surface reflection on both sides of an optical medium. The size of the microcavity changes the wavelength of light. These changing characteristics allow UV OLEDs with narrower emission spectra to be tuned to specific wavelengths to sense and excite light. When such OLED arrays are created, scientists can perform multivariate analysis and optical excitation on the same device.

Based on previous Ames Laboratory microcavity OLED research, researchers have created a device that can emit light in the wavelength range of 370~430nm (deep blue and near ultraviolet), expanding the research on visible light. Graduate student Eeshita Manna conducted the experiment, and Ames Laboratory scientist Rana Biswas simulated the spectra. In further research by former graduate student Emily Hellerich, they expanded the range to 470nm by combining two unique photopolymers: CBP and PVK. Combined with early research on visible microcavity OLED arrays, their current research can cover the range of 370~640 nm.