Ayaz Ali

Black phosphorus ink formulation for inkjet printing of optoelectronics and photonics.

Black phosphorus is a two-dimensional material of great interest, in part because of its high carrier mobility and thickness dependent direct bandgap. However, its instability under ambient conditions limits material deposition options for device fabrication. Here we show a black phosphorus ink that can be reliably inkjet printed, enabling scalable development of optoelectronic and photonic devices. Our binder-free ink suppresses coffee ring formation through induced recirculating Marangoni flow, and supports excellent consistency (< 2% variation) and spatial uniformity (< 3.4% variation), without substrate pre-treatment. Due to rapid ink drying (< 10 s at < 60 °C), printing causes minimal oxidation. Following encapsulation, the printed black phosphorus is stable against long-term (> 30 days) oxidation. We demonstrate printed black phosphorus as a passive switch for ultrafast lasers, stable against intense irradiation, and as a visible to near-infrared photodetector with high responsivities. Our work highlights the promise of this material as a functional ink platform for printed devices.Atomically thin black phosphorus shows promise for optoelectronics and photonics, yet its instability under environmental conditions and the lack of well-established large-area synthesis protocols hinder its applications. Here, the authors demonstrate a stable black phosphorus ink suitable for printed ultrafast lasers and photodetectors.

A self-powered high-performance graphene/silicon ultraviolet photodetector with ultra-shallow junction: breaking the limit of silicon?

This work is supported by National Science Foundation (DMR1508144), NSFC (Grant Nos. 61274123, 61474099, 61674127,and 61431014), and micro-fabrication/nano-fabrication platform of ZJU University, and the Fundamental Research Funds for the Central Universities (2016XZZX001-05). This work is also supported by ZJU Cyber Scholarship and Cyrus Tang Center for Sensor Materials and Applications, the Open Research Fund of State Key Laboratory of Bioelectronics, Southeast University, the Open Research Fund of State Key Laboratory of Nanodevices and Applications at Chinese Academy of Sciences (No.14ZS01), and Visiting-by-Fellowship of Churchill College at University of Cambridge.

A Broadband Fluorographene Photodetector

High-performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine-functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid-infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp2 domains, and the trapping of photoexcited charge carriers in the localized states in sp3 domains. Tunable photoresponse is achieved by controlling the nature of sp3 sites and the size and fraction of sp3 /sp2 domains. In addition, the photoresponse due to the different photoexcited-charge-carrier trapping times in sp2 and sp3 nanodomains is determined. The proposed scheme paves the way toward implementing high-performance broadband graphene-based photodetectors.