Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > High-performance, NW-OPTs open the way for optoelectronic device miniaturization

 Schematic diagram of single-crystalline nanowire organic phototransistors

Copyright @ Wiley-VCH Verlag GmbH & Co. KGaA.
Schematic diagram of single-crystalline nanowire organic phototransistors

Copyright @ Wiley-VCH Verlag GmbH & Co. KGaA.

Abstract:
Research team of Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea, developed high-performance organic phototransistors (OPTs) based on single-crystalline n-channel organic nanowires.

High-performance, NW-OPTs open the way for optoelectronic device miniaturization

Ulsan, Republic of Korea | Posted on March 12th, 2013

Phototransistors are a kind of transistors in which the incident light intensity can modulate the charge-carrier density in the channel. Compared with conventional photodiodes, phototransistors enable easier control of light-detection sensitivity without problems such as the noise increment. However, to date, the research has mostly focused on thin-film OPTs, and nanoscale OPTs have scarcely been reported.

OPTs have many intrinsic advantages over their inorganic counterparts, such as the chemical tunability of optoelectronic properties by molecular design and high potential in low cost, light-weight, flexible applications.

Single-crystalline nano-/microwires (NWs/MWs) based on organic semiconductors have attracted great interest recently as they are promising building blocks for various electronic and optoelectronic applications. In particular, OPTs based on single-crystalline NWs/MWs may yield higher light sensitivity than their bulk counterparts. In addition, their one-dimensional, intrinsically defect-free and highly ordered nature will allow a deeper understanding of the fundamental mechanisms of charge generation and transport in OPTs, while enabling a bottom-up fabrication of optoelectronic nanodevices.

Prof. Joon Hak Oh and Hojeong Yu, working at UNIST, together with Prof. Zhenan Bao at Stanford University, USA, have worked on n-channel single-crystalline nanowire organic phototransistors (NW-OPTs) and observed significant enhancement in the charge-carrier mobility of NW-OPTs.

Prof. Oh said, "The development of OPTs based on n-channel single-crystalline organic semiconducting NWs/MWs is highly desirable for the bottom-up fabrication of complementary metal oxide semiconductor (CMOS)-like photoelectronic circuits, which provides various advantages such as high operational stability, easy control of photoswitching voltages, high photosensitivity and responsivity."

The photoelectronic characteristics of the single-crystalline NW-OPTs such as the photoresponsivity, the photo-switching ratio, and the photoconductive gain, were analyzed from the I-V characteristics coupled with light irradiation and compared with those of vacuum-deposited thin-film devices. The external quantum efficiencies (EQEs) were also investigated for the NW-OPTs and thin-film OPTs. In addition, they calculated the charge accumulation and release rates from deep traps, and investigated the effects of incident light intensity on their photoelectronic properties.

A mobility enhancement is observed when the incident optical power density increases and the wavelength of the light source matches the light-absorption range of the photoactive material. The photoswitching ratio is strongly dependent upon the incident optical power density, whereas the photoresponsivity is more dependent on matching the light-source wavelength with the maximum absorption range of the photoactive material.

NW-OPTs based on n-channel semiconductor, N,N ′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI), exhibited much higher external quantum efficiency (EQE) values (≈7900 times larger) than thin-film OPTs, with a maximum EQE of 263 000%. This phenomena result from the intrinsically defect-free single-crystalline nature of the BPE-PTCDI NWs. In addition, an approach was devised to analyze the charge-transport behaviors using charge accumulation/release rates from deep traps under on/off switching of external light sources.

"Our approach to charge-accumulation/release-rate calculations could provide a fundamental understanding about charge-carrier-density variations under light irradiation, which subsequently enables in-depth study of OPTs," said Prof. Oh, "Hence organic single-crystalline NW-OPTs are a highly promising alternative to conventional thin-film-type photodiodes, and can effectively pave the way for optoelectronic device miniaturization."

This research was supported by a National Research Foundation of Korea (NRF) Grant funded by the Ministry of Education, Science, and Technology (MEST), and the Global Frontier Research Center for Advanced Soft Electronics and published in Advanced Functional Materials (Title: High-Performance Phototransistors Based on Single-Crystalline n-Channel Organic Nanowires and Photogenerated Charge-Carrier Behaviors, 5 Feb 2013).

####

For more information, please click here

Contacts:
Eunhee Song

82-522-171-224

Copyright © Ulsan National Institute of Science and Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

The article can be found at:

Related News Press

News and information

Global Carbon Nanotubes Industry 2015: Acute Market Reports August 4th, 2015

Nanoparticles Give Antibacterial Properties to Machine-Woven Carpets August 4th, 2015

Promising Step Taken in Iran towards Treatment of Spinal Cord Injury August 3rd, 2015

Diagnosis of Salmonella Bacterium-Caused Food Poisoning by Biosensors August 3rd, 2015

Govt.-Legislation/Regulation/Funding/Policy

Small tilt in magnets makes them viable memory chips August 3rd, 2015

Vaccine with virus-like nanoparticles effective treatment for RSV, study finds August 3rd, 2015

MIPT researchers clear the way for fast plasmonic chips August 3rd, 2015

Nanoparticles used to breach mucus barrier in lungs: Proof-of-concept study conducted in mice a key step toward better treatments for lung diseases August 3rd, 2015

Chip Technology

Small tilt in magnets makes them viable memory chips August 3rd, 2015

Better together: Graphene-nanotube hybrid switches August 3rd, 2015

MIPT researchers clear the way for fast plasmonic chips August 3rd, 2015

Thin films offer promise for ferroelectric devices: Researchers at Tokyo Institute of Technology demystify the ferroelectric properties observed in hafnium-oxide-based thin films, revealing a potentially useful device material August 3rd, 2015

Discoveries

Nanoparticles Give Antibacterial Properties to Machine-Woven Carpets August 4th, 2015

Nanoparticles used to breach mucus barrier in lungs: Proof-of-concept study conducted in mice a key step toward better treatments for lung diseases August 3rd, 2015

Promising Step Taken in Iran towards Treatment of Spinal Cord Injury August 3rd, 2015

Diagnosis of Salmonella Bacterium-Caused Food Poisoning by Biosensors August 3rd, 2015

Announcements

Global Carbon Nanotubes Industry 2015: Acute Market Reports August 4th, 2015

Nanoparticles Give Antibacterial Properties to Machine-Woven Carpets August 4th, 2015

Promising Step Taken in Iran towards Treatment of Spinal Cord Injury August 3rd, 2015

Diagnosis of Salmonella Bacterium-Caused Food Poisoning by Biosensors August 3rd, 2015

Photonics/Optics/Lasers

MIPT researchers clear the way for fast plasmonic chips August 3rd, 2015

Heating and cooling with light leads to ultrafast DNA diagnostics July 31st, 2015

IEEE Photonics Society Applauds Rochester on Integrated Photonics Institute Win July 30th, 2015

March 2016; 6th Int'l Conference on Nanostructures in Iran July 29th, 2015

Research partnerships

University of Puerto Rico announces August 11th as the launch date for their NASA mission to look for life in space XEI reports August 3rd, 2015

Newly-Developed Polymers Control Size of Nanoparticles during Production Process July 30th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Spintronics: Molecules stabilizing magnetism: Organic molecules fixing the magnetic orientation of a cobalt surface/ building block for a compact and low-cost storage technology/ publication in Nature Materials July 25th, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project