image: Giant infrared bulk photovoltaic effect in tellurene for broad-spectrum neuromodulation a, Schematic of the atomic structure of Te; b, Photoresponse spectra of various semiconductors exhibiting BPVE. c, Power dependence of Jsc in reported materials under different light wavelengths. d, Co-culture process of mouse primary cortical neurons and Te nanoflakes. Red and cyan shapes represent mouse primary cortical neurons and Te nanoflakes, respectively. Deep red indicates electrophysiological recording traces showing changes in membrane voltage in primary cortical neurons co-cultured with Te nanoflakes when stimulated by infrared lasers. e, Illustration of the broad-spectrum neuromodulation mechanism between neurons and Te. The redox reaction occurs at the interface between Te and neurons. Purple and grey balls represent extracellular cations and intracellular anions, respectively. Red and grey hollow balls represent photogenerated electrons and holes, respectively. f. Quantification of the peak threshold of action potentials generated by primary cortical neurons co-cultured with Te nanoflakes.
Credit: by Zhen Wang, Chunhua Tan, Meng Peng, Yiye Yu, Fang Zhong, Peng Wang, Ting He, Yang Wang, Zhenhan Zhang, Runzhang Xie, Fang Wang, Shuijin He, Peng Zhou, and Weida Hu
Efficient light-to-electricity conversion is crucial in applications such as imaging, free-space communication, biological sensing, and clean energy. The bulk photovoltaic effect (BPVE) has garnered significant research interest due to its ability to surpass the Shockley-Queisser efficiency limit of p-n junction photovoltaic effects. Among the materials exhibiting BPVE, van der Waals materials with low dimensionality, strong symmetry breaking, and high compatibility have demonstrated exceptional characteristics. However, due to interband optical transitions in semiconductors and heterostructures, current BPVE responses are primarily confined to a narrow wavelength range from ultraviolet to visible light. While Berry curvature and scattering in semimetals can assist in generating infrared BPVE, the low probability of optoelectronic transitions induced by polarized single-wavelength laser light hinders further applications. Thus, the exploration of broadband BPVE remains a significant challenge. Additionally, traditional strategies for light-to-electricity conversion in optical neuromodulation are limited to a narrow wavelength range, making the exploration of broad-spectrum neuromodulation through alternative photoelectric effects a valuable and intriguing area of research.
In a new paper published in Light: Science & Applications, a team of scientists, led by Professor Weida Hu from State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences and co-worker, have reported a giant infrared bulk photovoltaic effect in tellurene (Te). Furthermore, they successfully achieved broad-spectrum neuromodulation using Te nanomaterials. The significance of this work includes three key points: (1) The generated photocurrent in uniformly illuminated Te nanomaterials with adjustable lengths ranging from 0.95 μm to 12.92 μm is attributed to the BPVE under an applied voltage of 0 V; (2) The BPVE in Te spans a wide wavelength range from ultraviolet (390 nm) to mid-infrared (3.8 µm), with a photocurrent density of 70.4 A cm⁻² under infrared light, outperforming previous ultraviolet, visible semiconductors, and infrared semimetals; (3) Due to the observed giant BPVE, Te nanomaterials attached to the dendrites or somata of cortical neurons can elicit action potentials under broad-spectrum light irradiation (637 nm, 940 nm, 1.31 µm, and 1.55 µm), comparable to electrical stimulation.
These scientists summarized their work as follows: “The giant infrared BPVE of Te and its broad-spectrum neuromodulation demonstrated in this study advance the understanding of BPVE in nanomaterials and their applications. This work provides a novel strategy to enhance the efficiency of narrow-bandgap nanomaterials in converting broadband light into electrical energy via infrared BPVE. It also addresses the major challenges of remote broad-spectrum neuromodulation, particularly in the near-infrared IIa (1.3-1.4 μm) region, and further establishes Te with infrared BPVE as a promising candidate for novel nano-modulation with significant potential in neurological disease treatment.”
Article Title
Giant infrared bulk photovoltaic effect in tellurene for broad-spectrum neuromodulation