U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: Behrang Hamadani (Fed)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 1 - 25 of 79

Observation and Analysis of Nine Orders of Magnitude Memory Window in pn GaN Regrowth Vertical Diodes

September 1, 2026
Author(s)
Stephen Moxim, Gelu Comanescu, Cooper Voigt, Ory Maimon, Behrang Hamadani, Andrew Winchester, Emily Bittle, Qiliang Li, Travis Anderson, Jennifer Hite, Albert Davydov, Jason Campbell, Sujitra Pookpanratana, Jason Ryan
Wide bandgap semiconductors, including gallium nitride (GaN), are crucial for next-generation power electronics due to their superior properties compared to silicon. However, challenges in their fabrication, particularly with epitaxial regrowth for

Comparative Analysis of Voltage Losses in Perovskite and GaAs Solar Cells at Low Temperatures

August 6, 2026
Author(s)
Hurriyet Yuce Cakir, Isaac Ogunniranye, Margaret A. Stevens, Matthew P. Lumb, Kenneth J. Schmieder, Susanna Thon, Zhaoning Song, Behrang Hamadani
This study presents a comparative analysis of the open circuit voltage behavior of perovskite vs. gallium arsenide (GaAs) solar cells at low temperatures relevant to space applications. While GaAs solar cells demonstrate high power conversion efficiencies

Redox-Buffering PEAI-CeOx Passivation Suppresses Thermo-Mechanical Degradation in Perovskite Solar Cells Under Rapid Thermal Cycling

July 27, 2026
Author(s)
George Asare, Minwoo Lee, Joshua Adu, Juhong Oh, Behrang Hamadani, Jae Sung Yun, Helen Park
Perovskite solar cells (PSCs) show critical thermo-mechanical and defect mediated degradation at interfaces, limiting their deployment in terrestrial high-temperature and space-like environments. This study presents a dual-function interfacial passivation

Controlling Phase Transition Dynamics in Laser-Printed Perovskite Films via Additive-Driven Strain Engineering

April 10, 2026
Author(s)
Hurriyet Yuce Cakir, Manikanta Makala, Ganga Neupane, Marielle Deconinck, Vladimir Shilovskikh, Xinyi Zhou, Rudolph Holley III, Quinn Burlingame, Yana Vaynzof, Yueh-Lin Loo, Behrang Hamadani, Oana Jurchescu
The structural phase transitions in hybrid perovskites are critical to their performance and stability, but controlling them remains a significant challenge. Here, we demonstrate that the dynamics of the low-temperature tetragonal-to-orthorhombic phase

Origin of the voltage gap and recombination losses in all-perovskite tandem solar cells

March 19, 2026
Author(s)
Hurriyet Yuce Cakir, John Roller, Haoran Chen, Tingting Zhu, Susanna Thon, Yanfa Yan, Zhaoning Song, Behrang Hamadani
All-perovskite tandem solar cells with narrow and wide bandgap perovskite absorbers are promising candidates for low-cost and high efficiency photovoltaic applications. However, the open circuit voltage of typical tandem structures is generally smaller

Comparison of Electroluminescence and Photoluminescence Imaging of Mixed-Cation Mixed-Halide Perovskite Solar Cells at Low Temperatures

February 16, 2026
Author(s)
Hurriyet Yuce Cakir, Haoran Chen, Isaac Ogunniranye, Susanna Thon, Yanfa Yan, Zhaoning Song, Behrang Hamadani
Mixed-cation mixed-halide perovskites have emerged as promising candidates for high-performance solar cells. This study investigates the temperature-dependent optoelectronic properties of Rb0.05Cs0.05MA0.05FA0.85Pb(I0.95Br0.05)3 perovskite solar cells

Tuning the Surface Electronic Landscape of Ultrathin (Al,Sn)Ox Electron Extraction Layers in Perovskite Solar Cells

April 10, 2025
Author(s)
Joshua Sraku Adu, Alice Sheppard, Raphael Agbenyeke, George Kwesi "Asare ", Behrang Hamadani, David Fermin, Helen Hejin Park
Power conversion losses at the electron transport layer (ETL) are key limiting factors in high-performance perovskite solar cells (PSC) and silicon-PSC tandem systems. Solution-processed nanoparticle tin dioxide (np-SnO2) films typically serve as ETLs in n

Insights into transient photovoltage lifetimes via dark J-V analysis in perovskite solar cells

September 23, 2024
Author(s)
Ganga Neupane, John Roller, Susanna Thon, Sheng Fu, Zhaoning Song, Yanfa Yan, Behrang Hamadani
Transient photovoltage (TPV) decay measurements have commonly been used to estimate the charge carrier lifetimes in solar cell devices. However, it has recently been demonstrated that an intrinsic material property such as the effective bulk carrier

Ozone generation and chemistry from 222 nm germicidal ultraviolet light in a fragrant restroom

May 20, 2024
Author(s)
Michael F. Link, Rileigh Robertson, Andrew Shore, Behrang Hamadani, Christina Cecelski, Dustin Poppendieck
Devices using 222 nm germicidal ultraviolet light (GUV222) have been marketed to reduce virus transmission indoors with low risk of occupant harm from direct UV exposure. GUV222 generates ozone, an indoor air pollutant and oxidant, under constrained

Electrical and Electroluminescence Evaluation of 17 Year Old Monocrystalline Silicon Building Integrated Photovoltaic Modules

December 25, 2023
Author(s)
Andrew Shore, Tali Schlenoff, Bakary Coulibaly, David Navon, Stephanie Moffitt, Brian P. Dougherty, Behrang Hamadani
Longterm reliable operation of photovoltaic modules is necessary to ensure the technology is key to reducing the cost of solar energy. However, degradation mechanisms in the field are not always consistent or predictable. We present a dataset of 72

Intra-grain local luminescence properties of CdSe0.1Te0.9 Thin Films

December 25, 2023
Author(s)
Ganga Neupane, Behrang Hamadani, David Albin, Joel Duenow, Matthew Reese, Susanna Thon
We report on the local photoluminescence properties of grains and grain boundaries of CdSe0.1Te0.9 thin film deposited by the colossal grain growth method using a wide-field hyperspectral imaging technique. We observed significant variations in the

Imaging local luminescence variations in CdSe0.1Te0.9 thin films grown by the colossal grain growth process.

August 4, 2023
Author(s)
Ganga Neupane, Andrew Winchester, Nicolas Marquez Peraca, David Albin, Joel Duenow, Matthew Reese, Sujitra Pookpanratana, Susanna Thon, Behrang Hamadani
Clear visualization and understanding of luminescence properties of grain interiors and grain boundaries in polycrystalline thin-film photovoltaic materials are crucial to achieving high-performance solar cells. Luminescence-based measurements, for example

Ozone Generation from a Germicidal Ultraviolet Lamp with Peak Emission at 222 nm

July 21, 2023
Author(s)
Michael F. Link, Andrew Shore, Behrang Hamadani, Dustin Poppendieck
Recent interest in commercial devices containing germicidal ultraviolet lamps with a peak emission wavelength at 222 nm (GUV222) has focused on mitigating virus transmission indoors while posing minimum risk to human tissue. However, 222 nm light can

What limits the voltage of GaAs photovoltaic devices under low indoor light?

June 19, 2023
Author(s)
Behrang Hamadani, Margaret Stevens, Matthew Lumb, Kenneth Schmieder
The external radiative efficiency of a photovoltaic device is a useful metric to compare different photovoltaic technologies and material systems. However, under low-intensity indoor lighting, a particular open-circuit voltage dependence arises that cannot

Hyperspectral Imaging of Localized, Optically-Active Defects in GaAs Solar Cells

November 14, 2022
Author(s)
Behrang Hamadani, Margaret Stevens, Brianna Conrad, Matthew Lumb, Eric Armour, Kenneth Schmieder
A novel hyperspectral imaging instrument with dual electroluminescence and photoluminescence capability was used to image and analyze localized radiative defects in rear-junction GaAs solar cells grown at 1 µm/min. The absolute photon emission rates were

Visualizing Localized, Radiative Defects in GaAs Solar Cells

September 1, 2022
Author(s)
Behrang Hamadani, Margaret Stevens, Brianna Conrad, Matthew Lumb, Kenneth Schmieder
We have used a calibrated, wide-field hyperspectral imaging instrument to obtain absolute spectrally and spatially resolved photoluminescence images in high growth-rate, rear-junction GaAs solar cells from 300 K to 77 K. At the site of some localized

Color-Temperature Dependence of Indoor Organic Photovoltaic Performance

March 5, 2022
Author(s)
Boya Zhang, Justin Bonner, Lakshmi Murthy, Thien Nguyen, Fong-Yi Cao, Yen-Ju Cheng, Behrang Hamadani, Julia Hsu
Organic materials are uniquely suited for indoor light energy harvesting because they absorb mostly in the visible spectrum and the absence of ultraviolet light minimizes their degradation. However, the performance of photovoltaic devices under indoor
Was this page helpful?