Polymer LEDs as tunnel diodes: mechanism and device operation

1994 ◽  
Author(s):  
I.D. Parker ◽  
Yang Yang ◽  
Chi Zhang ◽  
Q.B. Pei ◽  
A.J. Heeger
Keyword(s):  
Tunnel Diodes ◽  
Polymer Leds ◽  
Device Operation

Symmetrically Configured AC Light-Emitting (Scale) Devices: Generalizations and Variations

1995 ◽  
Vol 413 ◽  
Author(s):  
Y. Z. Wang ◽  
D. D. Gebler ◽  
A. J. Epstein ◽  
H. L. Wang ◽  
T. M. Swager ◽  
...  
Keyword(s):  
Electrode Materials ◽  
Emeraldine Base ◽  
Driving Voltage ◽  
Tunnel Diodes ◽  
Device Structure ◽  
Insulating Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Insulating Polymers ◽  
Device Operation

ABSTRACTMost conjugated polymer-based light-emitting devices have been shown to be tunnel diodes which can only operate under forward DC driving field. Recently we have reported the fabrication of symmetrically configured AC light-emitting (SCALE) devices based on heterocyclic aromatic conjugated polymers. By adding an “insulating” layer (e.g. emeraldine base (EB) form of polyaniline) on both sides of the emitting layer, the SCALE devices emit light under both forward and reverse DC bias as well as AC driving voltage. The SCALE device structure ITO/J/emitterFl/M, has been shown to be quite general, and can be applied to a variety of electroluminescent polymers (emitter), insulating polymers (I) and electrode materials (M). Here we summarize and compare the performance of SCALE devices fabricated with different emitter, insulator, and electrode materials. The role of the insulating layer in the SCALE device operation is examined and a model that emphasizing the interface states is proposed to account for the device operation.

Analysis of the Bias Dependent Spectral Response of a-SiC:H p-i-n Photodiode

2002 ◽  
Vol 715 ◽  
Author(s):  
P. Louro ◽  
A. Fantoni ◽  
Yu. Vygranenko ◽  
M. Fernandes ◽  
M. Vieira
Keyword(s):  
Bias Voltage ◽  
Voltage Dependence ◽  
Spectral Response ◽  
Surface Recombination ◽  
Electrical Field ◽  
Field Reversal ◽  
Current Voltage ◽  
Voltage Dependent ◽  
And Inversion ◽  
Device Operation

AbstractThe bias voltage dependent spectral response (with and without steady state bias light) and the current voltage dependence has been simulated and compared to experimentally obtained values. Results show that in the heterostructures the bias voltage influences differently the field and the diffusion part of the photocurrent. The interchange between primary and secondary photocurrent (i. e. between generator and load device operation) is explained by the interaction of the field and the diffusion components of the photocurrent. A field reversal that depends on the light bias conditions (wavelength and intensity) explains the photocurrent reversal. The field reversal leads to the collapse of the diode regime (primary photocurrent) launches surface recombination at the p-i and i-n interfaces which is responsible for a double-injection regime (secondary photocurrent). Considerations about conduction band offsets, electrical field profiles and inversion layers will be taken into account to explain the optical and voltage bias dependence of the spectral response.

Energetic Control of Redox-Active Polymers Towards Safe Organic Bioelectronic Materials

2019 ◽  
Author(s):  
Alexander Giovannitti ◽  
Reem B. Rashid ◽  
Quentin Thiburce ◽  
Bryan D. Paulsen ◽  
Camila Cendra ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Organic Semiconductors ◽  
Side Reaction ◽  
Semiconducting Polymers ◽  
Side Reactions ◽  
Redox Active ◽  
Donor Acceptor ◽  
Electrochemical Devices ◽  
Biological Environment ◽  
Device Operation

<p>Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side‑products. This is particularly important for bioelectronic devices which are designed to operate in biological systems. While redox‑active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side‑reactions with molecular oxygen during device operation. We show that this electrochemical side reaction yields hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), a reactive side‑product, which may be harmful to the local biological environment and may also accelerate device degradation. We report a design strategy for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevent the formation of H<sub>2</sub>O<sub>2</sub> during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte‑gated devices in application-relevant environments.</p>

Growth aspects of AlGaAs/GaAs tunnel diodes for multijunction solar cells

2005 ◽  
Vol 40 (10-11) ◽  
pp. 1039-1042 ◽  
Author(s):  
G. Timò ◽  
C. Flores ◽  
R. Campesato
Keyword(s):  
Solar Cells ◽  
Tunnel Diodes ◽  
Multijunction Solar Cells

scholarly journals Long-lived charge separation following pump-wavelength–dependent ultrafast charge transfer in graphene/WS2 heterostructures

2021 ◽  
Vol 7 (9) ◽  
pp. eabd9061
Author(s):  
Shuai Fu ◽  
Indy du Fossé ◽  
Xiaoyu Jia ◽  
Jingyin Xu ◽  
Xiaoqing Yu ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Separation ◽  
Transient Absorption ◽  
Transition Metal Dichalcogenides ◽  
Thermionic Emission ◽  
Great Promise ◽  
Metal Dichalcogenides ◽  
Ultrafast Charge Transfer ◽  
Device Operation ◽  
Interfacial Charge

Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo-thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the performance of optoelectronic devices, in particular photodetection.

scholarly journals Beehive Air Sampling and Sensing Device Operation in Apicultural Applications—Methodological and Technical Aspects

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4019
Author(s):  
Andrzej Szczurek ◽  
Monika Maciejewska
Keyword(s):  
Gas Sensing ◽  
Operation Mode ◽  
Air Sampling ◽  
Sampling Point ◽  
Sampling System ◽  
Point Selection ◽  
Bee Colony ◽  
Temporal Aspects ◽  
High Quality Information ◽  
Device Operation

The basis of effective beekeeping is the information about the state of the bee colony. A rich source of respective information is beehive air. This source may be explored by applying gas sensing. It allows for classifying bee colony states based on beehive air measurements. In this work, we discussed the essential aspects of beehive air sampling and sensing device operation in apicultural applications. They are the sampling method (diffusive vs. dynamic, temporal aspects), sampling system (sample probe, sampling point selection, sample conditioning unit and sample delivery system) and device operation mode (‘exposure-cleaning’ operation). It was demonstrated how factors associated with the beehive, bee colony and ambient environment define prerequisites for these elements of the measuring instrument. These requirements have to be respected in order to assure high accuracy of measurement and high-quality information. The presented results are primarily based on the field measurement study performed in summer 2020, in three apiaries, in various meteorological conditions. Two exemplars of a prototype gas sensing device were used. These sensor devices were constructed according to our original concept.

Degradation of Ge-Doped and Zn-Doped GaAs Tunnel Diodes

1968 ◽  
Vol 7 (8) ◽  
pp. 875-880 ◽  
Author(s):  
Hidekichi Satoh ◽  
Tetsuji Imai
Keyword(s):  
Tunnel Diodes

Conjugated Polymer Surfaces and Interfaces for Light-Emitting Devices

MRS Bulletin ◽  
1997 ◽  
Vol 22 (6) ◽  
pp. 46-51 ◽  
Author(s):  
W.R. Salaneck ◽  
J.L. Brédas
Keyword(s):  
Conjugated Polymers ◽  
Photoelectron Spectroscopy ◽  
Electronic Materials ◽  
Structural Information ◽  
Molecular Solids ◽  
Chemical Modeling ◽  
Polymer Leds ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Surfaces And Interfaces

Since the discovery of high electrical conductivity in doped polyacetylene in 1977, π-conjugated polymers have emerged as viable semiconducting electronic materials for numerous applications. In the context of polymer electronic devices, one must understand the nature of the polymer surface's electronic structure and the interface with metals. For conjugated polymers, photoelectron spectroscopy—especially in connection with quantum-chemical modeling—provides a maximum amount of both chemical and electronic structural information in one (type of) measurement. Some details of the early stages of interface formation with metals on the surfaces of conjugated polymers and model molecular solids in connection with polymer-based light-emitting devices (LEDs) are outlined. Then a chosen set of issues is summarized in a band structure diagram for a polymer LED, based upon a “clean calcium electrode” on the clean surface of a thin film of poly(p-phenylene vinylene) (PPV). This diagram helps to point out the complexity of the systems involved in polymer LEDs. No such thing as “an ideal metal-on-polymer contact” exists. There is always some chemistry occurring at the interface.

Optimum design of InGaP/GaAs dual-junction solar cells with different tunnel diodes

2009 ◽  
Vol 41 (8) ◽  
pp. 605-612 ◽  
Author(s):  
J. W. Leem ◽  
Y. T. Lee ◽  
J. S. Yu
Keyword(s):  
Solar Cells ◽  
Optimum Design ◽  
Tunnel Diodes
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