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SUMMARY:Uncovering Synthesis Pathways and Defect Chemistry in Ternary Coppe
 r Selenide Photovoltaic Materials
LOCATION:Yates 102/103
TZID:America/Denver
DTSTART:20260512T160000
UID:2026-07-09-09-44-37@natsci.colostate.edu
DTSTAMP:20260709T094437
Description:Seminar Abstract:\nTernary copper chalcogenide semiconductors c
 an offer promising optoelectronic properties\, but their performance is of
 ten hampered by crystallographic defects that are difficult to identify wi
 th standard laboratory characterization. This seminar explores the relatio
 nship between synthetic pathways and atomic-scale disorder in two ternary 
 copper selenide materials\, Cu3PSe4 and Cu2SiSe3.\nWe first look at the st
 ructural evolution of the colloidal Cu-P-Se nanoparticle system using sync
 hrotron X-ray diffraction and Pair Distribution Function (PDF) analysis of
  aliquots taken at intervals throughout the reaction. We explore the local
  environment of phosphorus en route to Cu3PSe4 nanoparticle formation by r
 efining structural models against synchrotron data. Our analysis supports 
 the hypothesis that phosphorus remains local by occupying Cu-sites as anti
 site defects within intermediate Cu-Se binary phases\, which appears to fa
 cilitate the ultimate formation of the ternary Cu3PSe4 phase.\nContinuing 
 the investigation of synthesis routes and local structure in ternary coppe
 r selenide materials\, this talk highlights also the challenges of synthes
 izing the bulk\, zinc-blende-derived material\, Cu2SiSe3\, and its defects
 . This material is of particular interest due to its theoretically predict
 ed “tolerance” to the deleterious antisite defects common in other zin
 c-blende-derived materials\, such as CZTS and CIG(S\,Se). To avoid the lon
 g reaction times\, impurities\, and other synthetic limitations imposed by
  traditional solid state and flux methods\, we leverage thermodynamic driv
 ing forces using a gas-phase metathesis route for the successful synthesis
  of Cu2SiSe3. Additionally\, we discuss our ongoing efforts using high-res
 olution structural modeling to determine if Cu2SiSe3 successfully resists 
 antisite defect formation as predicted. Furthermore\, we address the appea
 rance of additional reflections in experimental powder X-ray diffraction (
 PXRD) patterns that\, along with transmission electron microscopy (TEM) ob
 servations\, suggest the presence of extended defects\, such as stacking f
 aults\, under certain synthetic conditions but not others. Future work aim
 s to investigate these hypothesized extended defects using stacking fault 
 simulations\, continued structural investigation via TEM\, and electronic 
 property measurements. By coupling the investigation of diverse synthetic 
 methods with rigorous defect analysis\, this work highlights the fundament
 al links between synthetic approaches and resulting atomic-scale structure
  of these photovoltaic materials. 4:00 pm
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