Tanaka Precious Metal Technologies and Nagoya University Develop Lead-Free Silver Quantum Dots for Shortwave Infrared Sensing, With Samples From January 2027
What Tanaka and Nagoya University developed for shortwave infrared sensing
Quentir Medicine Monitor
Evidence-based insights for quantum medicine.
Tanaka Precious Metal Technologies and the Torimoto Laboratory at Nagoya University have developed lead-free quantum dots made of silver, sulfur and tellurium that respond to near-infrared and shortwave infrared light. The company says it will begin supplying samples of the material in January 2027 and expects uses in consumer electronics and in the medical field.
The announcement went out on 20 October 2026. In Tanaka's own test, a simple light sensor that used the silver, sulfur and tellurium dots as its light-absorbing layer reached a maximum external quantum efficiency of 18.4 percent for light between 1,200 and 1,700 nanometers, according to Dellows News' Japanese-language article based on the company's release. The trade journal Compound Semiconductor reported the same figures on 20 October, along with the two conferences where the material will be shown: Okinawa Colloids from 1 to 6 November and nano tech 2026 in Tokyo from 16 to 18 December.
The work addresses a materials problem that has slowed infrared sensing for years. The standard detector material for this band, indium gallium arsenide, detects light out to about 1,700 nanometers with high sensitivity. It is made with vacuum processes, which makes yield and cost hard to control in volume, and Tanaka notes that indium supply is under pressure from demand in other advanced industries. Quantum dots of lead sulfide can be printed over large areas instead, and the release says sensors made that way cost about one tenth as much as indium gallium arsenide sensors.
Lead is the catch. The European Union's RoHS Directive restricts ten substances in electrical and electronic equipment, with lead and cadmium among them, and it applies to every product with an electrical or electronic component unless that product is specifically excluded. Tanaka says the lead content of lead sulfide dots has limited their use in consumer electronics. The new dots contain neither lead nor cadmium and still cover a similar range of wavelengths.
For readers in medicine, the interest lies in the wavelengths. The release states that light between 1,200 and 1,700 nanometers passes readily into materials and into the inside of the body, is less affected by sunlight and bad weather, and is safer for the human eye. It lists biological sensing among the applications, alongside smartphone face recognition, 3D sensing, wearable devices and automotive lidar. Those are the company's general statements about the band. How deep the light reaches and what exposure is safe depend on wavelength, tissue and light intensity, and the announcement offers no medical-device safety data.