Graphene-black phosphorus printed photodetectors

Layered materials (LMs) produced by liquid phase exfoliation (LPE) can be used as building blocks for optoelectronic applications. However, when compared with mechanically exfoliated flakes, or films prepared by chemical vapor deposition (CVD), LPE-based printed optoelectronic devices are limited by mobility, defects and trap states. Here, we present a scalable fabrication technique combining CVD with LPE LMs to overcome such limitations. We use black phosphorus inks, inkjet-printed on graphene on Si/SiO₂, patterned by inkjet printing based lithography, and source and drain electrodes printed with an Ag ink, to prepare photodetectors (PDs). These have an external responsivity (R _ext)∼337 A W⁻¹ at 488 nm, and operate from visible (∼488 nm) to short-wave infrared (∼2.7 µm, R ext ∼ 48 mA W⁻¹). We also use this approach to fabricate flexible PDs on polyester fabric, one of the most common used in textiles, achieving R ext ∼ 6 mA W⁻¹ at 488 nm for an operating voltage of 1 V. Thus, our combination of scalable CVD and LPE techniques via inkjet printing is promising for wearable and flexible applications.