How can we see clearly beneath the waves without an external power source? This question has long challenged researchers, as traditional photodetectors for underwater optical communication and imaging rely on battery-consuming bias voltages—a major drawback in the deep sea. Now, a team from Northeast Normal University in China has developed a self-powered blue-light photodetector that not only operates at zero bias, paving the way for low-power underwater imaging and optical sensing. The work has been published in the journal Nano Research on July 15.
Blue light is the ideal carrier for underwater wireless communication because it suffers the least absorption in seawater. However, existing blue photodetectors often require external power supplies, limiting their deployment in energy-scarce underwater environments. “We wanted to create a detector that harvests light energy itself, without any external battery,” explains Prof. Yuanzheng Li, corresponding author. “At the same time, we needed to boost its sensitivity to blue light to overcome the attenuation and scattering inherent in water.”
The team turned to multilayer tungsten disulfide (WS 2 ), a two-dimensional transition metal dichalcogenide known for its strong intrinsic absorption in the blue spectral region thanks to a band-nesting effect that generates high-energy C excitons. To further amplify the photoresponse, they decorated the WS 2 layer with silver nanoparticles (Ag NPs), which exhibit localized surface plasmon resonance (LSPR) at around 405 nm, matching the blue-light wavelength. “The LSPR effect does two things: it enhances the local electromagnetic field near the WS 2 , creating more electron–hole pairs, and it injects hot electrons directly into the semiconductor,” says Assoc. Prof. Yuanzheng Li, co-corresponding author. “This synergy between plasmons and excitons is the key to our performance.”
The device features an asymmetric electrode design forming a unilateral Schottky junction. This built-in electric field efficiently separates photogenerated carriers even at zero bias, enabling true self-powered operation. Under 405 nm illumination, the detector delivers a responsivity of 244 mA/W and an external quantum efficiency (EQE) of 74.7%—one of the highest reported for self-powered blue photodetectors. Its response time is in the sub-millisecond range (650 μs rise, 581 μs fall), and it maintains stable performance over hundreds of cycles, even after water exposure.
To demonstrate practical utility, the researchers integrated the device into a single-pixel imaging system. They placed a test pattern (“H”) in air, clear water, and turbid water, respectively, and reconstructed 128×128 pixel images using Hadamard modulation. Unsurprisingly, blue light produced the clearest images in both water conditions, while red and green light suffered from scattering and absorption. Quantitative analysis using peak signal-to-noise ratio (PSNR) gave a value of 25.5 dB in turbid water, which is a figure indicating good image quality suitable for real-world tasks. “This is the first demonstration of a self-powered WS 2 -based detector achieving high-resolution underwater single-pixel imaging,” notes Dr. Zhou. “It proves that our device can work in realistic murky environments without any external power, which is a game-changer for autonomous underwater vehicles and marine monitoring.”
Ultrafast transient absorption spectroscopy further revealed the microscopic mechanism: the LSPR effect significantly prolongs the lifetime of high-energy excitons, while the built-in field rapidly extracts carriers before they recombine. The team also quantified the relative contributions of near-field enhancement and hot-electron injection, showing that both play essential roles.
Looking ahead, the researchers believe their strategy can be extended to other wavelengths and applications, from deep-sea exploration to biomedical imaging. “Our work not only sets a new benchmark for blue-light detection but also provides a general blueprint for energy-autonomous optoelectronic systems,” concludes Assoc. Prof. Li. “The next step is to integrate this detector into compact underwater optical communication modules, bringing us closer to a fully self-sustained underwater internet of things.”
Other contributors include Jixiu Li, Chenmeng Zhao, Chuxin Yan, Yongsheng Gao and Wei Xin from Northeast Normal University. The research was supported by the National Natural Science Foundation of China (Nos. 12474421 and 12274065), the Science and Technology Development Plan Project of Jilin Province, China (Nos. 20260101043JJ), and the Fund from Jilin Province (No. JJKH20262151BS).
DOI Link:
https://doi.org/10.26599/NR.2026.94909030
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.
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