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Search Publications by: Behrang Hamadani (Fed)

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Displaying 51 - 75 of 79

Modulated photocurrent spectroscopy of CdTe/CdS solar cells-equivalent circuit analysis

May 20, 2013
Author(s)
Behrang H. Hamadani, John F. Roller, Kounavis Panagiotis, Nikolai B. Zhitenev, David J. Gundlach
We have used the technique of photocurrent modulated spectroscopy to investigate the dynamic response of charge carrier transport in thin film CdTe/CdS solar cells as a function of light bias and temperature over a broad excitation frequency range. The

High-Resolution Local Current Measurement of CdTe Solar Cells

October 4, 2012
Author(s)
Heayoung Yoon, Dmitry A. Ruzmetov, Paul M. Haney, Marina S. Leite, Behrang H. Hamadani, Albert A. Talin, Nikolai B. Zhitenev
We investigate local electronic properties of CdTe solar cells using electron beam to excite electron-hole pairs and evaluate spatially resolved photocurrent characteristics. Standard semiconductor processes were used to fabricate Ohmic metal contacts on

Towards realization of a large-area, LED-based solar simulator

November 27, 2011
Author(s)
Behrang H. Hamadani, Kangbin Chua, John F. Roller, Howard W. Yoon, Brian P. Dougherty
LED-based solar simulators have shown great promise as alternative light sources for indoor testing of PV cells as compared to their traditional counterparts. However, large-area uniform illumination more suitable for larger cells and module measurements

Imaging of nanoscale charge transport in bulk heterojunction solar cells

June 17, 2011
Author(s)
Behrang H. Hamadani, Nadine E. Gergel-Hackett, Paul M. Haney, Nikolai B. Zhitenev
We have studied the local charge transport properties of organic bulk heterojunction solar cells based on the blends of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) with a photoconductive atomic force microscope (PCAFM). We

Three-Dimensionally Structured CdS/CdTe Photovoltaics on Dual Interdigitated Back-Contacts

April 8, 2011
Author(s)
Carlos M. Hangarter, Behrang Hamadani, Ryan F. Need, Carlos R. Beauchamp, Hua Xu, John E. Bonevich, Nikolai Zhitenev, Daniel Josell
The fabrication and properties of three-dimensionally structured CdS/CdTe solar cells with back-contacts are described. Fabrication entails electrodeposition of CdS at submicrometer length scales on one of two metal electrodes interdigitated in a comb

Flexible Titanium Dioxide Memory

April 25, 2010
Author(s)
Nadine Gergel-Hackett, Laurie Stephey, Barbara Dunlap, Behrang Hamadani, David Gundlach, Curt Richter

Origin of Nanoscale Variations in Photoresponse of an Organic Solar Cell

April 22, 2010
Author(s)
Behrang H. Hamadani, Suyong S. Jung, Paul M. Haney, Lee J. Richter, Nikolai B. Zhitenev
Photo generated charge transport in bulk heterojunction (BHJ) solar cells is strongly dependent on the active layer nanomorphology resulting from phase segregation and connectivity of the donor and acceptor regions. Scanning probe-based techniques and in

Three-Dimensionally Structured Thin Film Heterojunction Photovoltaics on Interdigitated Back-Contacts

February 1, 2010
Author(s)
Daniel Josell, Carlos R. Beauchamp, Behrang H. Hamadani, Suyong S. Jung, Jonathan E. Guyer, Abhishek Motayed, Carlos M. Hangarter, Nadine E. Gergel-Hackett, Hua Xu, Nikolai B. Zhitenev
Fabrication and properties of three-dimensionally structured back-contact heterojunction solar cells are described. A variety of devices are explored, all of which were fabricated by electrochemical deposition of a semiconducting material on one of two

Flexible Memristors

December 3, 2009
Author(s)
Nadine E. Gergel-Hackett, Laurie A. Stephey, Barbara Dunlap, Behrang H. Hamadani, David J. Gundlach, Curt A. Richter

Flexible Memristors

December 3, 2009
Author(s)
Nadine Gergel-Hackett, Laurie Stephey, Barbara Dunlap, Behrang Hamadani, David Gundlach, Curt Richter

Nanoscale Photoresponse in Blended Organic Photovoltaics

August 16, 2009
Author(s)
Behrang H. Hamadani, Suyong S. Jung, Nikolai B. Zhitenev
Organic solar cells, which have attracted considerable interest over the last few years as low-cost, simply-processed alternatives for harvesting the solar energy, have interesting nanoscale properties; a thorough understanding of which is currently

Three-Dimensionally Structured CdTe Thin Film Photovoltaic Devices with Self-Aligned Back Contacts: Electrodeposition on Interdigitated Electrodes.

June 25, 2009
Author(s)
Daniel Josell, Carlos R. Beauchamp, Suyong S. Jung, Behrang H. Hamadani, Abhishek Motayed, Lee J. Richter, Maureen E. Williams, John E. Bonevich, Alexander J. Shapiro, Nikolai B. Zhitenev, Thomas P. Moffat
Cadmium-telluride photovoltaic cells were deposited on substrates patterned with two interdigitated electrodes. Deposition involved application of different potentials to the two electrodes in order to obtain a 3-d gradient of film properties within the

Substrate-dependent interface composition and charge transport in films for organic photovoltaics

June 9, 2009
Author(s)
David Germack, Calvin Chan, Behrang Hamadani, Lee J. Richter, Daniel A. Fischer, David J. Gundlach, Dean DeLongchamp
The buried interface composition of polymer-fullerene blends is found by near edge X ray absorption fine structure (NEXAFS) spectroscopy to depend on the surface energy of the substrate upon which they are cast. The interface composition determines the

Flexible Solution-Processed Memristors

June 3, 2009
Author(s)
Nadine E. Gergel-Hackett, Behrang H. Hamadani, B Dunlap, John S. Suehle, Curt A. Richter, Christina A. Hacker, David J. Gundlach
We have fabricated physically flexible nonvolatile memory devices using inexpensive, room-temperature, solution processing. The behavior of these devices is consistent with that of a memristor device, the missing fourth circuit element theoretically

Semiconducting Thienothiophene Copolymers: Design, Synthesis, Morphology and Performance in Thin Film Organic Transistors

March 1, 2009
Author(s)
Iain McCulloch, Martin Heeney, Michael L. Chabinyc, Dean DeLongchamp, Regis J. Kline, Michael Colle, Warren Duffy, Daniel A. Fischer, David J. Gundlach, Behrang Hamadani, Rick Hamilton, Lee J. Richter, Alberto Salleo, Martin Shkunov, David Sparrowe, Steve Tierney, Weimin Zhang
Organic semiconductors are emerging as a viable alternative to amorphous silicon in a range of thin film transistor devices. , With the possibility to formulate these p-type materials as inks and subsequently print into patterned devices, organic based

Surface Potential Imaging of Solution Processable Acene-Based Thin Film Transistors

December 2, 2008
Author(s)
Lucile C. Teague, Behrang H. Hamadani, John E. Anthony, David J. Gundlach, James G. Kushmerick, Sanker Subramanian, Thomas Jackson, Curt A. Richter, Oana Jurchescu
We report scanning Kelvin probe microscopy (SKPM) of electrically biased difluoro bis(triethylsilylethynyl) anthradithiophene (diF-TESADT) organic thin film transistors. SKPM reveals the relationship between the diF-TESADT film structure and device

High Performance Organic Thin-Film Transistors Made Simple Through Molecular Design and Processing

October 17, 2008
Author(s)
Oana Jurchescu, Marina Feric, Behrang H. Hamadani, M. Devin, Sankar Subramanian, Balaji Purushothamanc, John E. Anthony, Thomas Jackson, David J. Gundlach
We report on a simple a method of inducing self-isolation of the thin film transistors via manipulation of the chemical interactions between the organic molecules and the surfaces where they are deposited. We use pentafluorobenzenethiol (PFBT) treatment of

Correlation Between Microstructure, Electronic Properties and Ficker Noise in Organic Thin Film Transistors

March 31, 2008
Author(s)
Oana Jurchescu, Behrang H. Hamadani, Hao Xiong, Sungkyu Park, Sankar Subramanian, Neil M. Zimmerman, John E. Anthony, Thomas Jackson, David J. Gundlach
We report on observations of a direct correlation between the microstructure of the organic thin films and their electronic properties when incorporated in field-effect transistors. We present a simple method to induce enhanced grain growth in solution

Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits

March 8, 2008
Author(s)
David J. Gundlach, James E. Royer, SK Park, Sankar Subramanian, Oana Jurchescu, Behrang H. Hamadani, Andrew Moad, Regis J. Kline, LC Teague, Oleg A. Kirillov, Curt A. Richter, Lee J. Richter, Sean R. Parkin, Thomas Jackson, JE Anthony
The use of organic materials presents a tremendous opportunity to significantly impact the functionality and pervasiveness of large-area electronics. Commercialization of this technology requires reduction in manufacturing costs by exploiting inexpensive
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