Radical smart imaging sensor developed using quantum technology

The device uses new, low-carbon footprint technology that mimics the human brain and vision system, with huge potential for next-generation semiconductor imaging sensors.

Cardiff researchers have developed a new type of image sensor, able to carry out next-generation imaging known as neuromorphic vision, using colloidal quantum dots.

Inspired by the human retina, neuromorphic vision combines image sensing with memory to enable pre-processing functions such as colour recognition, visual memorising and forgetting.

Although there has been rapid development in the production of optoelectronic devices capable of neuromorphic vision, they have typically used toxic quantum materials and resulted in high-carbon footprints.

The technique has huge potential for healthcare, robotics vision, machine vision, industrial automation, consumer electronics and autonomous vehicles.

Dr Bo Hou, Senior lecturer at Cardiff University’s School of Physics and Astronomy who led the research said: “We have developed a solution-processed colloidal quantum dots image sensor, which can be modulated by manipulating light pulse intensity, frequency, wavelength, and gate voltage."

“As a demonstration, a phototransistor array effectively implements image pre-processing functions, including colour recognition, visual memorising, and forgetting."

“This could significantly strengthen the already flourishing leadership of the South Wales semiconductor cluster, and underpin future development in neuromorphic computing and neuromorphic image sensing."

“These semiconductor devices hold tremendous potential as key building blocks for next-generation computing, sensing and imaging semiconductor technology.”

The Cardiff team have succeeded in creating a neuromorphic image sensor using low-toxic CuZnInSSe (CIZS) colloidal quantum dots and amorphous InGaZnO (IGZO).

Colloidal quantum dots are solution-processed semiconducting nanocrystals – with diameters as small as 2-10 nanometers (one billionth of a metre)  –  whose properties can be tuned by their physical size.

This is the first time that colloidal CIZS quantum dots have been used as an active layer for neuromorphic vision, providing a less carbon-intensive means of developing image sensors with this capability.

Based in the state-of-the-art labs at Cardiff University’s new Translational Research Hub (TRH), the team are now focusing on high-performance neuromorphic imaging sensors based on low-carbon colloidal quantum dots and quantum wells.

They say that this will enable industry to implement the solution-processed colloidal semiconductor nanocrystals into their technologies to boost their resolution, efficiency, bandwidth and quantum efficiency and expect to share progress in the near future.

The study, funded by the Engineering and Physical Science Research Council (EPSRC) “SWIMS” project and Royal Society International Collaboration Awards, is published in the journal Advanced Optical Materials.

Paper: A Low-Toxic Colloidal Quantum Dots Sensitized IGZO Phototransistor Array for Neuromorphic Vision Sensors. Adv. Optical Mater. 2024, 2302451.