Robust Visible-Blind Wearable Infrared Sensor Based on IrP2 Nanoparticle-Embedded Few-Layer Graphene and the Effect of Photogating.

It is challenging to realize a visible-blind infrared photodetector as the materials that absorb infrared light also absorb visible light. Here, we report the synthesis of IrP2 nanoparticle-embedded few-layer graphene by one-step solid-state pyrolysis and its application in visible-blind infrared sensing. A linear photodetector device was fabricated by drop casting IrP2 nanoparticle-embedded few-layer graphene onto a flexible PET substrate with two gold electrodes separated by ∼16 μm. The photoconductive gain was found to be as high as ∼145% with response and decay times of ∼0.4 and ∼2.8 s, respectively, under 1550 nm irradiation of 800 mW cm-2. The room-temperature responsivity was ∼1.81 A W-1 at 80 mW cm-2 and ∼0.54 A W-1 at a high incident power of ∼2200 mW cm-2 under a bias of 1 V. Interestingly, the device showed response even in the long-wavelength infrared region, but no response was found under visible light. The embedded IrP2 nanoparticles act as trap centers inducing photogating in the device, and the average trap state energy was estimated to be ∼16.5 ± 1.5 meV from the temperature-dependent photocurrent studies. The device was found to be immune to air exposure and bending, suggestive of use a a wearable sensor.