Colloidal quantum dots (QDs) with infrared (IR) absorption and emission are promising candidates for next-generation optoelectronic applications, such as solar concentrators, light-emitting diodes, optical communication systems, biological imaging, and night or fog vision devices.¹ To date, the best-performing IR QDs have been based on Pb- and Hg-chalcogenides, whose synthesis protocols are now well established.² However, the inherent toxicity and environmental concerns associated with these materials limit their suitability for consumer and biomedical technologies, prompting a shift toward less toxic alternatives.³ Indium arsenide (InAs) QDs present a viable alternative due to their RoHS compliance and size-tunable bandgap, which spans a broad spectral range from 700 to more than 1700 nm.⁴ Despite their potential, early InAs QD syntheses relied on the use of pyrophoric, expensive, and commercially limited arsenic precursors. This challenge was mitigated with the introduction of tris(dimethylamino)arsine (amino-As), a non-pyrophoric, cost-effective As precursor.⁵ The key characteristic of amino-As is that it requires the use of a reducing agent to convert As³⁺ to As^3-, which is necessary for the formation of InAs.

Despite the advances made with amino-As synthesis routes, achieving InAs QDs with high photoluminescence (PL) quantum yield (QY) beyond 1000 nm remains challenging.⁶ Moreover, syntheses using amino-As typically rely on reducing agents that are either low-boiling or dissolved in volatile solvents, leading to reaction instability, including temperature fluctuations, and hazardous boiling bursts.

To address these limitations, we synthesized a novel high-boiling reducing agent, which enabled the development of stable and scalable reaction pathways for amino-As-based InAs QDs. In detail, we could produce InAs QDs with excitonic absorption peaks tunable down to 935nm, which, after ZnSe shelling, exhibited impressive PLQys of 75% (at 905 nm) and 60% (at 1000 nm). Larger InAs QDs, with excitonic absorption and emission extending into the short-wave infrared (SWIR) region, were also synthesized by developing a seeded growth approach to increase the QD size. Remarkably, the thermal stability of our reducing agent enables continuous precursor injection without triggering boiling-related issues. Upon ZnSe shelling QDs with record PLQYs of 46% at 1160 nm, 38% at 1250 nm, 32% at 1335 nm, and 23% at 1430 nm were achieved. 

These advancements collectively establish a robust, scalable, cost-effective, and safer synthetic route for producing highly luminescent InAs QDs with tunable emission spanning the near-IR to SWIR. This work significantly advances the practical viability of InAs-based nanocrystals for integration into next-generation IR optoelectronic applications, including biomedical diagnostics, environmental sensing, and telecommunications.