Van der Waals materials with narrow energy gaps and efficient response over a broadband optical spectral range are key to widen the energy window of nanoscale optoelectronic devices. Here, we characterize FePS₃ as an appealing narrow-gap p-type semiconductor with an efficient broadband photo-response, a high refractive index, and a remarkable resilience against air and light exposure. To enable fast prototyping, we provide a straightforward guideline to determine the thickness of few-layered FePS₃ nanosheets extracted from the optical transmission characteristics of several flakes. The analysis of the electrical photo-response of FePS₃ devices as a function of the excitation energy confirms a narrow gap suitable for near IR detection (1.23 eV) and, more interestingly, reveals a broad spectral responsivity up to the ultraviolet region. The experimental estimate for the gap energy is corroborated by ab-initio calculations. An analysis of photocurrent as a function of gate voltage and incident power reveals a photo-response dominated by photogating effects. Finally, aging studies of FePS₃ nanosheets under ambient conditions show a limited reactivity of the outermost layers of flakes in long exposures to air.

具有窄能隙和在宽带光谱范围内有效响应的范德华材料是扩大纳米级光电器件能量窗口的关键。在这里，我们将FePS ₃表征为具有高效宽带光响应，高折射率以及对空气和光线的显着回弹力的吸引人的窄间隙p型半导体。为了实现快速原型制作，我们提供了一条直接的指南来确定从几片薄片的光透射特性中提取的几层FePS ₃纳米片的厚度。FePS ₃的电光响应分析器件作为激发能的函数，确认了一个适合于近红外检测的窄间隙（1.23 eV），更有趣的是，它揭示了直至紫外区域的宽光谱响应度。间隙能量的实验估计值通过从头算得到了证实。对作为栅极电压和入射功率的函数的光电流的分析表明，光响应受光闸效应的影响。最后，FePS ₃纳米片在环境条件下的老化研究表明，薄片的最外层在长时间暴露于空气中的反应性有限。