Toward Self-Powered NIR Photodetection with Commercial InAs Quantum Dots
Why this work?
Near-infrared (NIR) photodetectors are increasingly important for applications ranging from optical sensing and imaging to biomedical technologies, wearable systems, and emerging optoelectronic platforms.
However, many high-performance NIR photodetectors still rely on epitaxially grown semiconductors or quantum dots containing elements such as Hg or Cd, which can introduce challenges related to fabrication complexity, cost, scalability, and material sustainability.
In our recent work, we explored a different route: using commercially available indium arsenide (InAs) quantum dots with their native ligands preserved as the active NIR absorber.
Rather than developing a highly customized quantum-dot synthesis specifically for one device, we asked a practical question:
Can commercially available InAs quantum dots be directly integrated into a simple solution-processed architecture to achieve self-powered NIR photodetection?
What did we build?
We developed a solution-processed heterojunction photodetector with the architecture:
ITO / ZnO / InAs QDs / PTAA / Ag
The ZnO electron-transport layer and PTAA hole-transport layer were engineered to create a favorable energetic cascade around the InAs QD absorber and facilitate photogenerated carrier separation.
A central objective was to enable the device to operate without an externally applied electrical bias.
The resulting photodetector successfully operates in a self-powered mode at 0 V.
What did we observe?
The device exhibits photoresponse from the visible region into the near-infrared, with detection extending toward 1300 nm.
This spectral range is particularly interesting because it approaches the NIR-II biological window, where longer-wavelength light can provide advantages for several optical sensing and biomedical applications.
At zero external bias, the device shows measurable responsivity under both visible and NIR illumination, demonstrating that the heterojunction can separate and collect photogenerated carriers without requiring an external power supply.
But photocurrent alone does not provide the full picture of photodetector performance.
We therefore investigated several complementary aspects of device operation, including:
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External quantum efficiency
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Transient photoresponse
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Experimental noise characteristics
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Electrochemical impedance spectroscopy
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Photostability under prolonged NIR illumination
The photodetector exhibits a microsecond-scale photoresponse, demonstrating relatively fast carrier dynamics under self-powered operation.
Looking beyond conventional responsivity measurements
One important part of this study was the analysis of the device's electrical dynamics through electrochemical impedance spectroscopy (EIS).
The impedance response provides additional information about charge-transfer resistance, interfacial transport, and capacitive processes occurring within the multilayer photodetector.
We also experimentally characterized the electrical noise instead of relying exclusively on idealized shot-noise assumptions.
This distinction is important because realistic photodetector performance depends not only on responsivity but also on the actual noise generated by the complete device architecture.
By combining responsivity, transient response, noise analysis, EIS, EQE, and stability measurements, we aimed to provide a more complete understanding of how this InAs-QD heterojunction operates.
Why are commercial InAs quantum dots particularly interesting?
One of the most attractive aspects of this work is the use of commercially available InAs quantum dots.
In many nanomaterial-based photodetectors, the active material itself requires highly specialized synthesis, extensive ligand exchange, or complex chemical processing before device fabrication.
Here, the InAs QDs were incorporated while preserving their native ligands, demonstrating that commercially accessible nanocrystals can already provide a functional starting point for NIR optoelectronic devices.
This could help reduce the gap between nanomaterial development and practical device implementation.
Why does self-powered operation matter?
Operating a photodetector at 0 V offers several potential advantages.
It can reduce power consumption, simplify electronic integration, and become particularly attractive for autonomous sensors, distributed sensing systems, wearable technologies, and low-power optoelectronic platforms.
In our device, the built-in electric field generated by the heterojunction enables photogenerated carrier separation without an externally applied bias.
Where can this approach go next?
The present device should be considered a platform rather than a final performance limit.
There remains significant room for improvement through:
Ligand engineering · Interface optimization · Quantum-dot film morphology · Energy-level alignment · Optical-field management · Encapsulation · Charge-transport-layer engineering
Further progress in these areas could enhance responsivity, stability, noise performance, and overall detectivity.
At the same time, combining InAs quantum dots with advanced optical structures could provide additional opportunities for enhancing light absorption while maintaining an ultrathin and solution-processable device architecture.
The broader perspective
Our results demonstrate that commercial InAs quantum dots can serve as functional active materials for solution-processed, self-powered NIR photodetectors extending toward 1300 nm.
More broadly, this work highlights the potential of combining commercially accessible semiconductor nanocrystals with carefully engineered charge-selective interfaces to develop scalable next-generation photodetection platforms.
We hope this study contributes to ongoing efforts toward accessible, low-power, solution-processed NIR and NIR-II optoelectronics.
Read the full article
Near-Infrared photodetectors based on commercial InAs quantum dots
Optical Materials (2026)
Article: https://doi.org/10.1016/j.optmat.2026.118448
I would be very interested to hear your thoughts on the potential of InAs quantum dots for self-powered NIR photodetection, particularly regarding interface engineering, stability, and future integration with advanced optical architectures.