66 research outputs found
Metal-insulator-semiconductor heterostructures for plasmonic hot-carrier optoelectronics
Plasmonic hot-electron devices are attractive candidates for
light-energy harvesting and photodetection applications. For solid state
devices, the most compact and straightforward architecture is the metalsemiconductor
Schottky junction. However convenient, this structure
introduces limitations such as the elevated dark current associated to
thermionic emission, or constraints for device design due to the finite
choice of materials. In this work we theoretically consider the metalinsulator-semiconductor
heterojunction as a candidate for plasmonic hotcarrier
photodetection and solar cells. The presence of the insulating layer
can significantly reduce the dark current, resulting in increased device
performance with predicted solar power conversion efficiencies up to 9%.
For photodetection, the sensitivity can be extended well into the infrared by
a judicious choice of the insulating layer, with up to 300-fold expected
enhancement in detectivity.Peer ReviewedPostprint (published version
Large-Area Plasmonic-CrystalâHot-Electron-Based Photodetectors
In view of their exciting optoelectronic lightâ
matter interaction properties, plasmonicâhot-electron devices
have attracted significant attention during the last few years as a
novel route for photodetection and light-energy harvesting.
Herein we report the use of quasi-3D large-area plasmonic
crystals (PC) for hot-electron photodetection, with a tunable
response across the visible and near-infrared. The strong
interplay between the different PC modes gives access to intense
electric fields and hot-carrier generation confined to the metalâ
semiconductor interface, maximizing injection efficiencies with
responsivities up to 70 mA/W. Our approach, compatible with
large-scale manufacturing, paves the way for the practical
implementation of plasmonicâhot-electron optoelectronic devices.Peer ReviewedPostprint (published version
Inorganic Tin Perovskites with Tunable Conductivity Enabled by Organic Modifiers
Achieving control over the transport properties of charge-carriers is a
crucial aspect of realizing high-performance electronic materials. In
metal-halide perovskites, which offer convenient manufacturing traits and
tunability for certain optoelectronic applications, this is challenging: The
perovskite structure itself, poses fundamental limits to maximum dopant
incorporation. Here, we demonstrate an organic modifier incorporation strategy
capable of modulating the electronic density of states in halide tin
perovskites without altering the perovskite lattice, in a similar fashion to
substitutional doping in traditional semiconductors. By incorporating organic
small molecules and conjugated polymers into cesium tin iodide (CsSnI3)
perovskites, we achieve carrier density tunability over 2.7 decades, transition
from a semiconducting to a metallic nature, and high electrical conductivity
exceeding 200 S/cm. We leverage these tunable and enhanced electronic
properties to achieve a thin-film, lead free, thermoelectric material with a
near room-temperature figure-of-merit (ZT) of 0.21, the highest amongst all
halide perovskite thermoelectrics. Our strategy provides an additional degree
of freedom in the design of halide perovskites for optoelectronic and energy
applications
Advances in solution-processed near-infrared light-emitting diodes
Near-infrared light-emitting diodes based on solution-processed semiconductors, such as organics, halide perovskites and colloidal quantum dots, have emerged as a viable technological platform for biomedical applications, night vision, surveillance and optical communications. The recently gained increased understanding of the relationship between materials structure and photophysical properties has enabled the design of efficient emitters leading to devices with external quantum efficiencies exceeding 20%. Despite considerable strides made, challenges remain in achieving high radiance, reducing efficiency roll-off and extending operating lifetime. This Review summarizes recent advances on emissive materials synthetic methods and device key attributes that collectively contribute to improved performance of the fabricated light-emitting devices
Edge stabilization in reduced-dimensional perovskites
Reduced-dimensional perovskites are attractive light-emitting materials due to their efficient luminescence, color purity, tunable bandgap, and structural diversity. A major limitation in perovskite light-emitting diodes is their limited operational stability. Here we demonstrate that rapid photodegradation arises from edge-initiated photooxidation, wherein oxidative attack is powered by photogenerated and electrically-injected carriers that diffuse to the nanoplatelet edges and produce superoxide. We report an edge-stabilization strategy wherein phosphine oxides passivate unsaturated lead sites during perovskite crystallization. With this approach, we synthesize reduced-dimensional perovskites that exhibit 97â±â3% photoluminescence quantum yields and stabilities that exceed 300âh upon continuous illumination in an air ambient. We achieve green-emitting devices with a peak external quantum efficiency (EQE) of 14% at 1000âcdâm-2; their maximum luminance is 4.5âĂâ104âcdâm-2 (corresponding to an EQE of 5%); and, at 4000âcdâm-2, they achieve an operational half-lifetime of 3.5âh.This publication is based in part on work supported by an award (KUS-11-009-21) from the King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund Research Excellence Program, by the Ontario Research Fund (ORF), by the Natural Sciences and Engineering Research Council (NSERC) of Canada, and by the US Department of Navy, Office of Naval Research (Grant Award No. N00014-17-1-2524). H.Y. acknowledges the Research Foundation-Flanders (FWO Vlaanderen) for a postdoctoral fellowship. E.B. gratefully acknowledges financial support by the Research Foundation-Flanders (FWO Vlaanderen). S.B. acknowledges financial support from European Research Council (ERC Starting Grant #815128-REALNANO). M.B.J.R. and J.H. acknowledge the Research Foundation-Flanders (FWO, Grants G.0962.13, G.0B39.15, AKUL/11/14 and G0H6316N), KU Leuven Research Fund (C14/15/053) and the European Research Council under the European Unionâs Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. [307523], ERC-Stg LIGHT to M.B.J.R. DFT calculations were performed on the IBM BlueGene Q supercomputer with support from the Southern Ontario Smart Computing Innovation Platform (SOSCIP). M.I.S. acknowledges the Banting Postdoctoral Fellowship program from the Natural Sciences and Engineering Research Council of Canada (NSERC). H.T. acknowledges the Netherlands Organisation for Scientific Research (NWO) for a Rubicon grant (680-50-1511)
Solution-processed semiconductors for next-generation photodetectors
Efficient light detection is central to modern science and technology.Current photodetectors mainly use photodiodes based on crystalline inorganic elementalsemiconductors, such as silicon, or compounds such as IIIâV semiconductors. Photodetectorsmade of solution-processed semiconductors â which include organic materials, metal-halideperovskites and quantum dots â have recently emerged as candidates for next-generation lightsensing. They combine ease of processing, tailorable optoelectronic properties, facile integrationwith complementary metalâoxideâsemiconductors, compatibility with flexible substrates andgood performance. Here, we review the recent advances and the open challenges in the field ofsolution-processed photodetectors, examining the topic from both the materials and the deviceperspective and highlighting the potential of the synergistic combination of materials and deviceengineering. We explore hybrid phototransistorsand their potential to overcome trade-offsin noise, gain and speed, as well as the rapid advances in metal-halide perovskite photodiodesand their recent application in narrowband filterless photodetection
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