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Department of Physics and Astronomy Collins Research Group

Chris and Elijah Present their Theses at the WSU Physics Symposium

Undergraduate physics majors Chris Lum and Elijah Allen presented posters of their thesis work in the Collins lab at the WSU Physics and Astronomy Fall 2023 Symposium.

Chris’ thesis is titled “Charge mobility of organic semiconductors.” Chris measured the hole mobility in the OLED polymer F8BT using the space charge limited current technique on devices he fabricated.

Elijah’s thesis is titled “Comparing solvent processes for organic solar cells.” Elijah measured radiative and non-radiative voltage losses in solar cells printed via different solvents using absorption spectroscopy and quantum efficiency techniques.

Congratulations to Chris and Elijah!

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

Elijah Allen and Chris Lum Receive Research Scholarships

Undergraduate physics majors Chistopher Lum and Elijah Allen have each received research scholarships to work on their thesis projects in the Collins Lab this summer. Chris was awarded the Ellen Hauge Abelson Endowed Scholarship in Sciences and Elijah was awarded the Leo Millam Undergraduate Research Scholarship. On top of the prestigious honor recognizing their potential as STEM leaders, they each receive $4000 to enable them to focus on their undergraduate research this summer which focuses on excited state dynamics in organic electronic devices. Congratulations!

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!