The quantum dot revolution is here, but not all quantum dots are created equal. With demand for lead-free alternatives rising, INFIQ® technology is pushing the standard for lead-free quantum dots (QDs) to new heights – bringing high-performance short-wave infrared (SWIR) capability closer to everyday consumer devices.
Lead-free QDs are poised to transform industries from consumer devices to renewable energy and beyond, and Quantum Science is at the forefront of this progress. With its groundbreaking INFIQ® lead-free QD technology – sensitive to wavelengths up to 1,550nm – the company is at the forefront of lead-free QD device performance and is continually pushing the boundaries of what’s possible in high-performance, heavy metal-free SWIR functionality.
Demand for lead-free QDs
Interest in SWIR imaging and sensing is growing rapidly. According to industry analysts Yole Group, the market for this technology will grow from $322 million in 2022 to $2.9 billion in 2028 as image sensor manufacturers realise the applications that SWIR sensitivity will unlock.
Infrared QDs represent the best solution for supporting this growth due to their performance, low cost, and scalability compared with competing technologies. Lead-free QDs will be particularly important as more than $2 billion of the projected SWIR market value in 2028 will come from consumer electronics integrating features like biometric facial recognition, 3D sensing, eye tracking and proximity detection in virtual or augmented reality. Regulatory and company brand policies mean this market cannot accept technology containing lead or other heavy metals commonly used in QD production.
This means that lead-free alternatives are required, but the same high level of QD performance is necessary, this can be easier said than done. Lead-free alternatives have existed for several years but have typically struggled to achieve the longer SWIR wavelengths and to match the performance of heavy metal formulations.
INFIQ® lead-free QD technology
INFIQ® stands apart in the world of lead-free infrared QD technology. For years, other QD manufacturers have struggled with controlling the growth of lead-free materials while maintaining size and shape control. Quantum Science’s world-class team of scientists and engineers has developed proprietary methods for synthesising lead-free QDs with unmatched performance and can precisely tune QD sizes and bandgaps to cover spectra from the visible to the infrared range. This results in exceptional QD materials and inks that are not subject to restrictions due to heavy metals.
INFIQ technology is unique in the market due to its combination of leading EQE, low dark current, and scalability, making it accessible and practical to Quantum Science’s partners. INFIQ® lead-free QDs have excitonic peaks tuneable to 1,550nm, far surpassing the previous industry limit of 1,200nm, granting them access to the section of the SWIR spectra required for most applications. These nanoparticles have narrow size distributions, dispersibility, and sensitivity as far as 1,700nm. At 1,100nm and 1,400nm, the materials exhibit impressive I-V and QE curves. The EQE curves for 1100 nm and 1400 nm are shown below in figure 1. The dark current density at -1V bias for these devices is also shown in table 1. This combination of EQE and dark current is the world leading performance for this class of quantum dots.
Figure 1 External quantum efficiency (EQE) of the Pb-free QD photodiodes, with peak EQE at 1100 nm = 25% and 1400 nm = 16%.
| Wavelength (nm) | EQE (%) at -1V | Dark current density (µA/cm2) at -1V |
| 1100 nm | 25 | 0.8 |
| 1400 nm | 16 | 7 |
At the heart of this performance is Quantum Science’s innovative production process. The company’s unique synthetic route for developing lead-free QDs means it can precisely control QD growth without compromising optical properties and avoids using hazardous pyrophoric precursor materials that present a spontaneous combustion risk on exposure to air. This not only makes the materials safer to work with, but it also aligns with environmental goals, making the technology an appealing prospect for more eco-conscious sensor manufacturers.
INFIQ® LF-QD inks
Quantum Science’s expertise in this technology means it can also produce lead-free QDs in ink form that address key challenges in QD sensor manufacturing. Rather than relying on time-consuming layer-by-layer deposition methods, INFIQ® QD inks enable QDs to be deposited in a single layer, saving time and resources and minimising the risk of defect formation.
INFIQ® lead-free QD inks are also specifically formulated to overcome stability problems that can plague other QD ink formulations. Quantum Science’s technology is stable in solution when stored in inert conditions, for over 3 months enabling routine shipment and supply to image sensor makers all over the world. These inks have also been proven to work on silicon wafers, facilitating large-scale SWIR image sensor manufacturing as less ink is required to coat larger wafers.
A total solution provider
Quantum Science is committed to leading innovation and supplying partners and customers with cutting-edge QD technology. Its groundbreaking approach has garnered recognition from major players in the consumer technology sector, who acknowledge INFIQ®’s safety, scalability, and ESG compliance. Today, the company can provide three main specifications of lead-free QDs to its customers, and further innovations are underway.
More than this, Quantum Science is not just a traditional QD business. The company is committed to being a full solution provider in the QD sensor field – not only manufacturing high quality materials, but developing high-performance devices tailored to customers’ specific needs. As well as QD device fabrication and testing, Quantum Science can conduct internal wafer processing, streamlining the pathway to the high-performance image sensors that the growing market demands. As a result, it can act as a comprehensive partner for businesses looking to push the frontier of SWIR and QD technology.
A lead-free future
INFIQ® lead-free QDs are set to transform consumer technology. From enabling advanced face ID in smartphones, to unlocking eye-safe AR and VR headsets, this technology is paving the way for exciting new features in everyday devices. With the first consumer SWIR technology predicted to appear in high-end smartphones within the next few years, Quantum Science is shaping the future of infrared sensing and imaging.