skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Light sources with bias tunable spectrum based on van der Waals interface transistors
Abstract Light-emitting electronic devices are ubiquitous in key areas of current technology, such as data communications, solid-state lighting, displays, and optical interconnects. Controlling the spectrum of the emitted light electrically, by simply acting on the device bias conditions, is an important goal with potential technological repercussions. However, identifying a material platform enabling broad electrical tuning of the spectrum of electroluminescent devices remains challenging. Here, we propose light-emitting field-effect transistors based on van der Waals interfaces of atomically thin semiconductors as a promising class of devices to achieve this goal. We demonstrate that large spectral changes in room-temperature electroluminescence can be controlled both at the device assembly stage –by suitably selecting the material forming the interfaces– and on-chip, by changing the bias to modify the device operation point. Even though the precise relation between device bias and kinetics of the radiative transitions remains to be understood, our experiments show that the physical mechanism responsible for light emission is robust, making these devices compatible with simple large areas device production methods.  more » « less
Award ID(s):
1807969 2039380
PAR ID:
10343160
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Nature Communications
Volume:
13
Issue:
1
ISSN:
2041-1723
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. The exploitation of Brillouin scattering, the scattering of light by sound, has led to demonstrations of a broad spectrum of novel physical phenomena and device functionalities for practical applications. Compared with optomechanical excitation by optical forces, electromechanical excitation of acoustic waves with transducers on a piezoelectric material features intense acoustic waves sufficient to achieve near-unity scattering efficiency within a compact device footprint, which is essential for practical applications. Recently, it has been demonstrated that gigahertz acoustic waves can be electromechanically excited to scatter guided optical waves in integrated photonic waveguides and cavities, leading to intriguing phenomena such as induced transparency and nonreciprocal mode conversion, and advanced optical functionalities. The new integrated electromechanical Brillouin devices, utilizing state-of-the-art nanofabrication capabilities and piezoelectric thin film materials, succeed guided wave acousto-optics with unprecedented device integration, ultrahigh frequency, and strong light-sound interaction. Here, we experimentally demonstrate large-angle (60°) acousto-optic beam deflection of guided telecom-band light in a planar photonics device with electromechanically excited gigahertz (∼11 GHz) acoustic Lamb waves. The device consists of integrated transducers, waveguides, and lenses, all fabricated on a 330 nm thick suspended aluminum nitride membrane. In contrast, conventional guided-wave acousto-optic devices can only achieve a deflection angle of a few degrees at most. Our work shows the promises of such a new acousto-optic device platform, which may lead to potential applications in on-chip beam steering and routing, optical spectrum analysis, high-frequency acousto-optic modulators, RF or microwave filters and delay lines, as well as nonreciprocal optical devices such as optical isolators. 
    more » « less
  2. Abstract Wide‐bandgap semiconductors (WBGS) with energy bandgaps larger than 3.4 eV for GaN and 3.2 eV for SiC have gained attention for their superior electrical and thermal properties, which enable high‐power, high‐frequency, and harsh‐environment devices beyond the capabilities of conventional semiconductors. Pushing the potential of WBGS boundaries, current research is redefining the field by broadening the material landscape and pioneering sophisticated synthesis techniques tailored for state‐of‐the‐art device architectures. Efforts include the growth of freestanding nanomembranes, the leveraging of unique interfaces such as van der Waals (vdW) heterostructure, and the integration of 2D with 3D materials. This review covers recent advances in the synthesis and applications of freestanding WBGS nanomembranes, from 2D to 3D materials. Growth techniques for WBGS, such as liquid metal and epitaxial methods with vdW interfaces, are discussed, and the role of layer lift‐off processes for producing freestanding nanomembranes is investigated. The review further delves into electronic devices, including field‐effect transistors and high‐electron‐mobility transistors, and optoelectronic devices, such as photodetectors and light‐emitting diodes, enabled by freestanding WBGS nanomembranes. Finally, this review explores new avenues for research, highlighting emerging opportunities and addressing key challenges that will shape the future of the field. 
    more » « less
  3. Abstract Organized nano‐ and microstructures of molecular semiconductors display interesting optical and photonic properties, and enhanced charge carrier mobilities, as compared to disordered thin films. However, known directed‐growth and self‐organization strategies cannot create structured molecular heterojunctions and cannot be practically incorporated into existing device fabrication routines to create large‐area optoelectronic devices. Here, an ultrathin (<2 nm) seed layer of the compound coronene creates 1D nanostructures of an electron‐transporting molecule (IFD) is shown, which possesses an intrinsic proclivity to form disordered thin films in the absence of the seed layer. It is revealed that nanostructured IFD films exhibit enhanced light absorption and emission, and greater electron mobilities, as compared to amorphous counterparts. This seed layer strategy creates uniform IFD nanowires over large areas of up to 18 mm2at low processing temperatures. Notably, the coronene seed layer creates IFD nanowires when applied over either oxide surfaces or predeposited organic layers, meaning that this structuring approach can be integrated into diode manufacturing routines to realize large‐area flexible optoelectronic devices. Flexible organic light‐emitting diodes and fullerene‐free organic solar cells containing IFD nanowires in the photoactive layer to demonstrate that molecular nanostructures can lead to robust, large‐area device arrays on flexible substrates being fabricated. 
    more » « less
  4. Metal-halide perovskites, in particular their nanocrystal forms, have emerged as a new generation of light-emitting materials with exceptional optical properties, including narrow emissions covering the whole visible region with high photoluminescence quantum efficiencies of up to near-unity. Remarkable progress has been achieved over the last few years in the areas of materials development and device integration. A variety of synthetic approaches have been established to precisely control the compositions and microstructures of metal-halide perovskite nanocrystals (NCs) with tunable bandgaps and emission colors. The use of metal-halide perovskite NCs as active materials for optoelectronic devices has been extensively explored. Here, we provide a brief overview of recent advances in the development and application of metal-halide perovskite NCs. From color tuning via ion exchange and manipulation of quantum size effects, to stability enhancement via surface passivation, new chemistry for materials development is discussed. In addition, processes in optoelectronic devices based on metal-halide perovskite NCs, in particular, light-emitting diodes and radiation detectors, will be introduced. Opportunities for future research in metal-halide perovskite NCs are provided as well. 
    more » « less
  5. Abstract Hybrid organic–inorganic perovskite light‐emitting devices (LEDs) have recently shown the characteristic dynamical behavior of light‐emitting electrochemical cells (LECs), with intrinsic ionic migration creating an electric double layer and internal p‐i‐n structure and by accumulation of ions at interfaces. Therefore, the development of perovskite light‐emitting and photovoltaic devices based on the concepts of LEC operation attracts much attention and clarifies general physical processes in perovskites. Here, new directions that can further improve perovskite optoelectronic devices and extend their functionalities using additive mobile ions are overviewed: 1) enhancing single‐layer LECs with lithium additives for increased efficiency and longer lifetime; 2) facilitating ionic motion in three‐layer perovskite LECs to create dual‐functional devices, operating as both LEC and solar cells; and 3) creating truly ambipolar LEC devices with carbon nanotubes as stable electrodes that leverage ionic doping. Taken together, the use of these approaches provides a strategy to create efficient, stable, and bright LECs, which use advantages of both LED and LEC operation. It is discussed that how the LEC behavior in perovskite LEDs can be further improved to address the long‐term challenges in perovskite optoelectronics, such as stability, through approaches like ionically reconfigurable host/guest systems. 
    more » « less