Si‐H Hydrosilane Reducing Agents for Size‐ and Shape‐Controlled InAs Colloidal Quantum Dots

InAs colloidal quantum dots (CQDs) are a promising heavy‐metal‐free material for infrared optoelectronic devices. However, their synthesis is limited by their reagents: the acutely toxic and difficult to source tris(trimethylsilyl)arsine ((TMS)₃As), as well as the strong reducing agents (e.g., Super Hydride). A reducing agent is introduced based on hydrosilanes (Si‐H) to address both challenges. A synthesis strategy with this agent is demonstrated, resulting in monodisperse InAs CQDs with a tunable first excitonic peak between 520 and 900 nm by hot injection, and between 900 and 1550 nm by continuous injection. Furthermore, by avoiding the use of carboxyl group‐containing compounds, such as oleic acid or indium acetate, the synthesis minimizes surface oxidation during InAs CQDs formation. The synthesized InAs CQDs are of high optoelectronic quality, with a lower concentration of deep trap states, as evident by the remarkable characteristics of photodetectors fabricated from these CQDs: low dark current (≈150 nA cm⁻²), external quantum efficiency (32% at 900 nm), and a fast photoresponse time (≈4.4 µs). The elimination of (TMS)₃As in the synthesis overcomes a key practical barrier for exploiting and exploring the properties of large InAs CQDs in optoelectronic applications.