Simplifying night vision with advanced electronics

Seeing the invisible may be easier than ever before. Technology already exists to convert invisible infrared radiation to visible wavelengths. It is applied for night vision, bioimaging, and general defense purposes. However, the traditional method to output a visible image from infrared input involves complex devices that limit resolution, efficiency, and mass production.

Rao et al. proposed an alternative method, a silicon-organic LED (Si-OLED) upconverter, that integrates the processes within the infrared-to-visible device, simplifying the structure and reducing cost while improving the resolution, sensitivity, and frame rate.

Typical infrared-to-visible devices use a photodetector array with readout integrated circuits to address each pixel and render images. Instead of requiring interconnected and aligned pixels, complicated readout circuits, and elaborate signal processing, the authors used a pixelated indium tin oxide (ITO) interface between a silicon detector and an organic LED.

“The pixelated ITO interface layer can effectively suppress the lateral current spreading at the interface and confine the spatial transport of photocarriers, resulting in improved resolution,” said author Ge Mu.

In addition to improved resolution, this design uses a silicon wafer that is compatible with complementary metal-oxide semiconductors for easy application in large-scale devices in a variety of fields.

“Our upconversion efficiency nearly reaches 10%, which is higher than many existing upconverters,” said Ge. “Our Si-OLED upconverters, with flexible and lightweight features, have the potential to be used in the wearable biomedical field, where not many upconversion devices can obtain flexible ability.”

Source: “Large-scale fabrication of CMOS-compatible silicon-OLED heterojunctions enabled infrared upconverters,” by Tianyu Rao, Qun Hao, Ge Mu, Tianling Qin, Yimei Tan, Pengfei Zhao, Dexi Kong, Menglu Chen, and Xin Tang, APL Photonics (2023). The article can be accessed at https://doi.org/10.1063/5.0138070 .