Quantum dots, tiny semiconductors with tunable properties, are redefining optoelectronics by advancing infrared sensing, bioimaging, solar energy, and more with greater efficiency and lower environmental costs.
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Nanoscale semiconductors
Quantum dots are nanomaterials with a high surface-to-volume ratio and discrete quantized energy levels in the density of states. These discrete energy levels can be fine-tuned by varying the materials and band gaps of the quantum dots. In doing so, nanoscale semiconductors can be useful for sensing, medical applications, and optoelectronic devices.
Typically composed of a semiconductor core and a stabilizing shell, quantum dots exploit quantum confinement, allowing them to absorb and emit light across specific wavelengths with exceptional precision. By selecting the appropriate core and shell materials, researchers can tailor quantum dot performance for specific environmental and functional requirements.1
Optoelectronics deals with the detailed study of the intricate reactions between light and electricity, allowing us to manipulate light, regulate its attributes, and harness its energy for specific applications.
Devices such as Organic Light Emitting Diodes (OLEDs) and high-power semiconductor lasers play a key role in modern technological advancements, and such optoelectronic devices are becoming key in various fields, including modern information technology and communication systems, high-speed data centers, medical imaging, the automotive and manufacturing sectors, and astronomy.2
Mercury Telluride (HgTe) Colloidal Quantum Dots for Infrared Detection
A promising material for IR optoelectronics is mercury telluride (HgTe) colloidal quantum dots. With their broad tunability and narrow energy transitions, HgTe QDs can operate across a wide spectral range while maintaining stability in ambient air, reaching up to hundreds of Terahertz. These combined properties allow the manufacturing of quantum dots without the need for controlled environments or pristine clean rooms, reducing cost and complexity.3
Surface chemistry techniques have matured sufficiently to enable controlled doping and inter-particle coupling, expanding the design space for device architectures. These features position HgTe quantum dots as a serious contender in advanced photodetection.
Improving the Performance of Optoelectronic Photodetectors
Recent work has focused on improving the detectivity of mid-infrared photodetectors using HgTe colloidal quantum dots and Purcell enhancement mechanisms. A study in ACS Nano used a metal-insulator-metal (MIM) resonator and a 1000 nm SiO2 layer on a gold substrate, and deposited HgTe quantum dots on a patterned nanoantenna array.
Simulations of the design predicted a 23-fold increase in absorption, peaking at 60 % at 2650 cm-1, and a 20-fold rise in local electric field intensity near antenna tips. Practical results using the fabricated photodetector described were close behind. Detectivity increased by a factor of 19, responsivity reached 0.6 A/W at 1V bias, and the overall performance exceeded commercial, uncooled sensors by a factor of 40. Furthermore, the peak specific detectivity for the MIM device was 15 times greater than the highest one ever attained in previous studies.4
These results demonstrate the efficacy of HgTe colloidal QDs for enhancing the performance of various optoelectronic devices, especially infrared photodetectors.
Boosting Bioimaging
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The unique optical and electrical properties of quantum dots make near-infrared quantum dot LEDs (NIR-QLEDs) highly optimized compared to conventional LEDs. Indium phosphide (InP) quantum dots possess a remarkable quality of color tuning across a wide range and exceptional emission properties.
In a recent study, researchers developed eco-friendly NIR-QLEDs using copper-doped indium phosphide/zinc selenide with highly tunable attributes specially optimized for bioimaging. A transparent indium tin oxide serves as a hole-injecting anode, while Cu-doped InP/ZnSe Core/Shell quantum dots are at the core of the device. Cu doping is crucial as it allows intra-gap accelerator states within the InP interface. The charge transport layer (CTLs) was composed of Zinc magnesium oxide (ZnMgO), making it highly stable.
Using this high-quality and eco-friendly oxide material, an improved emission peak was observed at 924 nm, along with a narrow full-width at half maximum (FWHM) of 81 nm. The ZnMgO enhanced the performance of the optoelectronic device, with the NIR-QLED achieving an external quantum efficiency (EQE) of approximately 16 %.
They also surpassed commercial benchmarks for peak radiance, 62 W sr-1 m-2 compared to a more typical 41-45, while operating at just 1.8 V. The device doesn’t contain any lead or cadmium, making it highly eco-friendly.5 The device is the first-of-its-kind high-performance NIR-QLED, which was also tested by capturing clear and high-quality images of blood vessels on the human hand. This non-invasive and highly efficient ready-to-use device could be key for enhancing optoelectronic devices used in all industrial fields.
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High-Performance Perovskite Solar Cells
The solar energy sector also benefits from this nanotechnology. By integrating quantum dots into their design, researchers have developed perovskite solar cells with excellent power conversion efficiencies (PCE).
One study introduced a perovskite solar cell using zinc oxide (ZnO) quantum dots as electron transport layers, with zwitterion capping ligands and ammonium halides for interfacial passivation. The resulting device had a conversion efficiency of 21.9 % and a fill factor of 80.3 %, outperforming many commercial equivalents.
Among various halide treatments, NH4F emerged as the most effective, leading to higher interfacial stability and better long-term performance: it maintained around 78 % of the initial peak PCE even after 250 operational hours.
The novel device using ZnO QDs revealed a PCE greater than that of traditional solar cells using SnO2.6. Its high efficiency was obtained without complex equipment for precise manufacturing, proving zwitterions to be highly useful ligands, with NH4F a highly efficient interfacial passivant for the novel ZnO QD-based solar cells.
While HgTe and InP quantum dots are advancing rapidly, as described in the case studies above, graphene-based quantum dots are still in the early stages of development, particularly for immunosensing and multifunctional optoelectronic systems. These QDs are held back by stability, functionalization, and reproducibility. However, research is ongoing, and their potential is still significant for biocompatible, conductive materials. 7
This nanotechnology has, overall, proved to be a massive advancement in the efficiency of optoelectronic devices, drawing technology closer to sustainability and low manufacturing costs.
Further Reading
- Agarwal, K. et. al. (2023). Quantum dots: an overview of synthesis, properties, and applications. Materials Research Express, 10(6), 062001. Available at: https://www.doi.org/10.1088/2053-1591/acda17
- Para, T. (2023). Optoelectronics: Recent Advances. Introductory Chapter: Optoelectronics. Intech Open. 978-1-83769-795-3. Available at: https://www.doi.org/10.5772/intechopen.1003224
- Sergeeva, K. et. al. (2024). The Rise of HgTe Colloidal Quantum Dots for Infrared Optoelectronics. Adv. Funct. Mater. 34. 2405307. Available at: https://www.doi.org/10.1002/adfm.202405307
- Caillas, A. et. al. (2024). Uncooled high detectivity mid-infrared photoconductor using HgTe quantum dots and nanoantennas. ACS nano, 18(12), 8952-8960. Available at: https://doi.org/10.1021/acsnano.3c12581
- Din, N. et. al. (2025). Highly efficient large-area quantum dot near-infrared light-emitting device for advanced non-invasive bioimaging. Nano Energy, 111316. Available at: https://doi.org/10.1016/j.nanoen.2025.111316
- Runjhun, R. et. al. (2024). High-Performance Perovskite Solar Cells with Zwitterion-Capped-ZnO Quantum Dots as Electron Transport Layer and NH4 X (X = F, Cl, Br) Assisted Interfacial Engineering. Energy & Environmental Materials, 7(5), e12720. Available at: https://www.doi.org/10.1002/eem2.12720
- Mimona, M. et. al. (2025). Quantum dot nanomaterials: Empowering advances in optoelectronic devices. Chemical Engineering Journal Advances. 21. 100704. Available at: https://doi.org/10.1016/j.ceja.2025.100704
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