Energy-efficient high-performance photodetector based on two-dimensional monolayer CrI3

Abstract

Chromium triiodide (CrI3) is a fascinating two-dimensional (2D) ferromagnet that enables the study of layer-dependent spintronics in semiconductor materials. Most reports on CrI3 focus on its magneto-optical and magneto-electrical properties, yet there is currently no comprehensive experimental investigation on its photoconductivity. In this work, layered CrI3 single crystals were exfoliated and used to construct a two-terminal photodetector. In this study, we compare the performance of monolayer and bulk CrI3 single-crystal photodetectors when irradiated using various wavelengths of visible light. The photodetector has a response time of down to 50 ms for both monolayer and bulk CrI3. The monolayer CrI3 exhibits a two-order enhancement in responsivity of up to 1.58 × 104 A/W under exposure to 460 nm light because of its larger current density and the reduced transit distance of the photogenerated carriers. In addition, the ITO-coated glass electrodes which are sealed by parafilm provides an enclosed nitrogen-filled cavity that prevents the degradation of the CrI3 flake and helps to improve its cyclic stability for over 100 cycles. Our study demonstrates that the 2D monolayer CrI3 single crystal shows excellent photodetection properties, which are better than or comparable to other recently reported FET-based 2D semiconductor photodetector. In addition, the two-terminal design is powered only by a small bias voltage of 1.0 V without the need for a gate electrode, which are typically operated at high levels of voltage of up to 60 V. © 2026 Elsevier B.V.