Aditya Malla

Shortwave infrared (SWIR) light‐emitting diodes (LEDs) are essential for next‐generation applications in machine vision, remote sensing, and communications; however, their performance in conventional bottom‐emission architectures is hampered by optical trapping in substrate modes and limited thermal dissipation on glass. In this work, we report high‐performance top‐emission quantum‐dot light‐emitting diodes (TQLEDs) based on colloidal lead sulphide (PbS) quantum dots that overcome these limitations. Critical to this architecture is the development of a high‐performance transparent conductive electrode optimized for the SWIR region. Integrating these electrodes into a low‐Q microcavity led to the modification of the far‐field radiation pattern, manifested by enhanced forward‐directed light emission and narrowed emission linewidth. Furthermore, the use of high‐thermal‐conductivity silicon as the carrier substrate enabled the devices to sustain significantly higher current densities compared to glass‐based counterparts. The synergy between resonant optical engineering and superior thermal management enabled a record‐high radiance exceeding 100 W sr ⁻¹ m ⁻² . Finally, we demonstrate the practical utility of these high‐flux emitters through the demonstration of active SWIR imaging of a see‐through undoped silicon wafer illuminated solely by active quantum‐dot LEDs (QLEDs). This work establishes top‐emission architectures on silicon as a viable pathway for integrated, high‐power infrared QLEDs.

InSb colloidal quantum dots combine a low bulk bandgap (0.17 eV) with a large exciton Bohr radius, enabling access to short-wave infrared wavelength within the quantum confinement regime, alongside strong covalent bonding, complementary metal-oxide semiconductor compatibility, and restriction of hazardous substances compliance. However, prior one-pot and hot-injection approaches yield broad size distributions and weak excitonic absorption, while continuous-injection methods improve spectral features but are restricted to small dot sizes (<1.2 μm excitonic peaks). Here, we introduce a monomer-concentration-controlled approach that produces narrow-size-dispersed InSb quantum dots tunable from 950 to 1900 nm with the sharpest excitonic absorption peaks reported to date. Their monodisperse nature allowed the emergence of heavy hole-light hole splitting evident in their optical absorption spectra. Leveraging these high-quality nanocrystals, we demonstrate short-wave infrared photodetectors achieving external quantum efficiencies of 22% at 1500 nm and 19% at 1580 nm, extending the spectral reach of III-V colloidal quantum dot photodetectors at this wavelength range.