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Department of Physics and Astronomy Collins Research Group

Devin publishes in-situ polysoap micelle nanostructure

Graduate student Devin Grabner’s work on characterizing in-situ nanostructure and loading of novel polysoap micelles has been published in Langmuir. The work reveals the impressive capture and loading of aromatic cargo for therapeutics and water purification.  In-situ characterization shows this is due to an open corona structure likely controlled through macroion charging.  The work titled “Molecular weight-independent “polysoap” nanostructure characterized via in-situ resonant soft X-ray scattering” was conducted in collaboration with Dr. Phillip Picket at the University of Southern Mississippi and NIST as well as former Collins Lab postdoc Dr. Terry McAfee now at Berkeley National Laboratory.  Congratulations to all authors!

Read the article Molecular Weight-Independent “Polysoap” Nanostructure Characterized via In Situ Resonant Soft X-ray Scattering | Langmuir (acs.org)

Acacia Patterson Defends her Master’s Project


Graduate student Acacia Patterson has successfully defended her Master’s Thesis Project titled “Morphology-driven comprehensive charge loss analysis of organic photovoltaics processed with non-halogenated solvents.” Her project focused on quantifying all fundamental losses in the model system PCDTBT:PCBM and correlating these to morphological changes from replacing the traditional toxic halogenated solvent processing with non-halogen processing. She plans to publish this work and continue on in the lab for a PhD in Materials Science. Congratulations Acacia!

New Additive Halts Runaway Crystallinity in OPVs published in ACS Energy Letters

New work on a better processing additive for OPVs lead by gradstudent Obaid Alqahtani has been published in ACS Energy Letters. The highest OPV efficiencies, now reaching 20% solar power conversion efficiency, are obtained by solvent additives that enhance nanodomain/crystallinity formation, but often result in runnaway crystallization with small processing fluctuations. the new work shows that a new solvent additive eliminates this problem while still enhancing device performance. Gradstudent Awwad Alotaibi as well as REU undergraduate student Michael Burnes are coauthors on the study, which was published in the American Chemical Society’s lead journal for energy research. Congratulations Obaid and coauthors!

Green Additive Limits Runaway Crystallinity in PM6:Y6 Organic Solar Cells but Causes Field-Independent Geminate Recombination | ACS Energy Letters

Devin Grabner – 2023 ALS User Meeting Invited Speaker & Planning Committee Member

Devin Grabner played a dual role at this year’s Advanced Light Source (ALS) User Meeting & Visioning Workshops. As a member of the Users’ Executive Committee, he helped organize the week’s plenary talks, events, and workshops, which celebrated the 30th anniversary of the first light and discussed the future of the ALS. In addition, Devin was invited to present his cutting-edge research on the development of a Liquid In-Situ Resonant Soft X-ray Scattering technique during the “X-Ray Scattering for Complex Materials and Interfaces at the ALS: Data Acquisition and Analysis” tutorial on the first day of the User Meeting. The meeting tutorials and visioning workshops were valuable opportunities to exchange ideas and insights on the latest developments in the field.

One of the highlights of the event was a lunch meeting with Dr. Dava Keavney, the Program Manager for X-ray Light Sources at the U.S. Department of Energy – Scientific User Facilities. Devin was among the group of researchers invited to discuss current U.S. Department of Energy policies and positions related to X-ray Light Sources such as the ALS. The photo below pictures the group, including Devin, and Dr. Dava Keavney (far right).

Devin Grabner Awarded Advanced Light Source Doctoral Fellowship

As a 5th-year Physics Ph.D. Candidate in our group, Devin Grabner has been awarded a prestigious doctoral fellowship at Berkeley National Laboratory – Advanced Light Source (LBNL – ALS).

An ALS Doctoral Fellowship allows student researchers to work at the frontier of synchrotron radiation research and to help advance state-of-the-art techniques and applications. Students who have passed their Ph.D. qualifying or comprehensive exams and advanced to candidacy can apply to spend a year in residence at LBNL, working closely with an ALS staff member. Fellows acquire hands-on scientific training and develop professional maturity to complement their doctoral research. Applicants must be full-time students currently enrolled in a Ph.D. program in the science or engineering disciplines and pursuing research that will benefit from ALS capabilities.

 

Obaid Alqahtani Passes his PhD Defense

Obaid Alqahtani successfully defended his PhD dissertation entitled “Structure-property correlations in heterojunction organic solar cells across material systems via synchrotron X-ray techniques”. He completed his candidacy with his PhD committee including advisor Assoc. Prof. Brian Collins (Chair), Prof. Katie Zhong, and Prof. Matthew McCluskey. Obaid will continue in the group this summer as a postdoc before teaching at Prince Sattam bin Abdulaziz University in Saudi Arabia in completion of his PhD Fellowship commitment.

Congratulations Obaid!

Collins Group Presents at 2019 APS March Meeting

Thomas Ferron, Victor Murcia, Terry McAfee, and Brian Collins all presented at the 2019 APS March Meeting in Boston, MA. Victor, Terry, and Brian all presented in the Focus Session on “Advanced Morphological Characterization in Polymers” where Brian gave the Invited Talk for the session.

Victor presented his work on combining NEXAFS measurements and DFT of molecules to create more accurate optical models for analysis of polarized resonant soft X-ray scattering (RSoXS). Terry discussed his work with developing in-situ capabilities in RSoXS showing quantitative characterization of polymer micelle structure and dynamics without using chemical labels.

Thomas presented in the Focus Session on Organic Electronics where he discussed his recent paper on charge separation affected by molecular mixing at the donor-acceptor interface in organic photovoltaic devices.

Thomas’ organic solar cell work published in J Materials Chemistry

Graduate student Thomas Ferron’s work tying molecular mixing at interfaces to charge generation in organic solar cells (OSC) has been published in Journal of Materials Chemistry A. The work quantifies for the first time both the volume of the mixed phase and the efficiency of separating interfacial Charge Transfer states into free charges. A better than 99% correlation is revealed between these two phenomena in a model OSC system – made possible because both nanostructure and excited state dyanmics were measured on the exact same devices. Thomas’ analysis, furthermore, eliminates all other possible contributing factors to the correlation – implying a causal relationship that sharper interfaces (less mixing) causes higher charge separation efficiencies.

Critical to the study was a relatively new optical pump-electronic probe technique known as Time-Delayed Collection Field (TDCF). Although the technique is increasingly done around the world, the Collins group is the only one capable of the measurement in the US.  This is Thomas’ second 1st-Author paper published and includes as coauthors a former Undergraduate physics major Matthew Waldrip and former Masters student Michael Pope. The work was funded by the US Department of Energy as an Early Research Career Award. Congratulations to all involved!

Obaid Alqahtani’s Solar Cell Work Published in Advanced Energy Materials

Obaid Alqahtani’s work on structure-property relationships in small molecule organic solar cells (SM-OSCs) has been officially published online at Advanced Energy Materials. SM-OSC devices convert sunlight into power like commercial solar panels, but this new technology could significantly lower the cost of solar power because it can be printed from inks in a roll-to-roll newspaper fashion, is light-weight and flexible, and is made from earth-abundant, non-toxic materials.

Alqahtani’s work explains how the performance of SM-OSCs depends on the details of the nanostructure, which can be tuned via processing solvent and choice of molecular side-chain. In particular, it is demonstrated that high purity nano-domains results in low/delayed charge generation and severe charge trapping, but that small, mixed domains alleviates such problems to enable high performance in these devices. Future work toward commercialization should target such nanostructure for high solar power conversion efficiencies.

The work involved a large round-robin collaboration with groups across the globe including King Abdullah University of Science and Technology (KAUST, Saudi Arabia), Stanford University (USA), University of Potsdam (Germany), and University of Queensland (Australia).

Read the Paper