Rational design of an ultra-high-gain MoS2 phototransistor enabling room-temperature detection of few-photon signals and attomolar-level immunosensing - PubMed (original) (raw)

. 2025 Nov 30;70(22):3812-3821.

doi: 10.1016/j.scib.2025.08.010. Epub 2025 Aug 11.

Yun Hui 2, Wenhua Zhou 3, Shengxuan Xia 4, Yawei Lv 5, Liwei Ouyang 6, Yang Chai 7, Xingqiang Liu 8, Bei Jiang 5, Chang Liu 5, Sen Zhang 5, Chenchen Chu 6, Ling Ji 9, Guoli Li 5, Xue-Feng Yu 10, Lei Liao 11, Xuming Zou 12

Affiliations

Rational design of an ultra-high-gain MoS2 phototransistor enabling room-temperature detection of few-photon signals and attomolar-level immunosensing

Zhengdao Xie et al. Sci Bull (Beijing). 2025.

Abstract

Determining the number of photons in an incident light pulse at room temperature is the ultimate goal of photodetection. Herein, we report a plasmon-strain-coupled tens of photon level phototransistor by integrating monolayer MoS2 on top of Au nanowire (NW). Within this structure, Au NW can greatly enhance incident light intensity around MoS2, and the large tensile strain can reduce the contact energy barrier between MoS2 and Au NW, so as to achieve efficient injection of plasmonic hot electrons into MoS2. Furthermore, ultrashort MoS2 channel significantly shortens the carrier transit time. As a result, the phototransistor with record optical gain (3.1 × 1011) can accurately determine Poissonian emission statistics of light source with tens of photon level resolution at room temperature. In addition, the phototransistor also demonstrates a broadband spectral sensitivity (0.37-1.55 μm), as well as intrinsic photon-polarization selection. Furthermore, an ultra-sensitive optical immunoassay (USOIA) platform is proposed using the phototransistor as photodetector. Coupled with specific antibody-conjugated quantum dot nanospheres and magnetic beads, the platform is able to detect the model biomarker, C-reactive protein, as low as 1.684 amol/L in serum samples with a dynamic range spanning 12 orders of magnitude. With its significantly enhanced sensitivity and simplicity, ultra-high-gain MoS2 phototransistor can pave the way toward optically ultra-sensitive determination of various biomarkers for early disease diagnosis.

Keywords: Attomolar-level-detection; High photogain phototransistor; Plasmon strain engineering; Tens of photon level resolution.

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