2021 RTNN Collaborative Research Award Winners Announced!

Congratulations to the winners of our 2021 RTNN Collaborative Research Award! This award seeks to identify outstanding research projects, papers, and/or presentations that leverage the resources, equipment, and/or expertise available through the RTNN. Awarded research projects are expected to demonstrate a high-level of research progress and achievement that was made possible only by the use of two or more university sites or collaborators within the RTNN. Dr. Jill Dempsey, Dr. Michael Mortelliti, and Annie Wang share this award for their innovative use of fabrication and analytical techniques available in RTNN to better understand materials used in photo-electrosynthesis cells (DSPECs).

Problem this work addressed: The performance of dye-sensitized photoelectrosynthesis cells (DSPECs) is significantly improved when a core/shell SnO2/TiOx photoanode is utilized, as opposed to simple TiO2 nanocrystalline films. This performance enhancement has been attributed to slower charge recombination dynamics due to electron tunneling from a core-localized electron to the oxidized dye. A fixed rectangular barrier tunneling model has been proposed, in which the SnO2 conduction band is ca. 300–500 mV more positive than that of TiO2. However, this model is based on several poor assumptions and further, this model is challenged by observations in the dye-sensitized solar cell community noting that treatment of TiO2 electrodes with a chemical bath of TiCl4 (to form a TiOx coating on the core material) also enhances device efficiency. If applying a fixed rectangular barrier model based on data from bulk single crystals, as is employed for SnO2/TiOx core/shell photoanodes, no barrier to electron transfer would be expected between an electron localized in the core TiO2 and the oxidized dye.

Key Findings: In this work, the researchers obtained a unified understanding of the mechanisms by which SnO2/TiOx and TiO2/TiOx core/shell materials facilitate improved device efficiency in DSPECs and DSSCs. Specifically, they report their use of atomic layer deposition (CHANL) to fabricate an array of TiO2/TiOx and SnO2/TiOx core/shell electrode materials with different shell thicknesses and different annealing temperatures. They comprehensively characterized the electronic structure of these materials using diffuse reflectance (CHANL), X-ray photoelectron spectroscopy (CHANL), and Raman spectroscopies in conjunction with high-resolution transmission electron microscopy (AIF), powder X-ray diffraction (CHANL), and reductive electrochemistry. They then quantified charge recombination dynamics of the dye-sensitized materials using transient absorption spectroscopy. From these data, a physical model was constructed for charge recombination in core/shell materials consistent with all these data.


Impact: By correlating how the electronic structure of the shell material is responsible for impeding charge recombination, this work answers a decade-long question about the mechanism by which anode shells and coatings improve DSPEC and DSSC device performance. This work shows how shell crystallinity and trap state density is critical in the recombination mechanism, emphasizing that there is a critical annealing temperature at which a balance is realized between slow recombination and fast diffusion to the back contact for optimum device performance. This understanding thus provides an explicit blueprint for shell fabrication to improve performance DSSCs and DSPECs.

This research made use of the instrumentation in both CHANL (UNC) and the AIF (NCSU). Further, research was also supported by a grant to high school student Annie N. Wang through the North Carolina Research Triangle Nanotechnology Network, Kickstarter Program.


This work is published in the following paper:

Interfacial Electron Transfer through Ultrathin ALD TiOx Layers: A Comparative Study of TiO2/TiOx and SnO2/TiOx Core/Shell Nanocrystals

Michael J. Mortelliti, Annie N. Wang, and Jillian L. Dempsey
The Journal of Physical Chemistry C 2021 125 (23), 12937-12959

DOI: 10.1021/acs.jpcc.1c02428

Apply now! RTNN Research Experience for Undergraduates, Summer 2022

The Research Triangle Nanotechnology Network is seeking applicants for their Summer 2022 Research Experience for Undergraduates program on hybrid perovskites!

Hybrid perovskites are exciting materials that enable state-of-the-art technology for solar cells, lighting, lasers and more. We are seeking undergraduate applicants to experience novel research on this topic during Summer 2022 under the guidance of renowned faculty at UNC-Chapel Hill, NC State University, and Duke University – all working together as the Research Triangle Nanotechnology Network (RTNN). Participating faculty span the departments of Chemistry, Physics, Materials Science, and Applied Science.

  • ~12 students will be supported for 10 weeks – starting late May through mid-August
  • Students will experience hands-on contemporary research topics on hybrid organic-inorganic materials including  synthesis and processing, modeling and characterization, and device fabrication and testing
  • Applicants must be enrolled in an undergraduate degree program and be a US Citizen or permanent resident
  • Students from diverse disciplines and backgrounds are encouraged to apply
  • Selected students will receive a $6,000 stipend in addition to on-campus housing at host institution and relevant travel expenses
  • Applications are due February 4 (letters of recommendation due February 18)
  • Applicants will be notified of acceptance by March 15

Please see our REU webpage for more information and to apply:




New Papers Published on Responsible Innovation of Nanotechnology in Food and Agriculture

RTNN collaborators Maude Cuchiara and Khara Grieger, among others, have published two new papers in NanoImpact addressing topics on responsible innovation for nano-agrifoods, as well as insights on barriers to responsible innovation from a study of US experts, stakeholders, and developers:

Responsible innovation of nano-agrifoods: Insights and views from U.S. stakeholders

  • Stakeholder views of responsible innovation and nano-agrifoods were investigated

  • Views were dominated by environmental, health, and safety contexts.

  • A subset of views emphasized a broader set of responsible innovation considerations.

  • Challenges included lack of safety studies, regulation, and public understanding and acceptance.

  • Future work should broaden considerations for responsible nano-agrifood innovation.

Barriers to responsible innovation of nanotechnology applications in food and agriculture: A study of US experts and developers


  • This study reports the first typology of barriers to responsible innovation as perceived by researchers and product developers working in nano-agrifood sectors.

  • Identified 5 key barriers: Lack of Data, Need for Ensuring Marketability & Use, Lack of Product Oversight, Need for Increased Collaboration, and Lack of Adequate Training & Workforce.

  • Elucidates tensions between theoretical values inscribed within responsible innovationand the practical R&D within nano-agrifood sectors.

  • Identifies opportunities to improve practices and process of responsible innovation across these innovation phases as they pertain to nano-agrifood sectors.


Congratulations to our 2021 Image Contest Winners

SEM image of a mosquito stylet

A big thank you to everyone who submitted an image in the 2021 Image Competition. We are excited to announce the winners. Please vote for these amazing images in the NNCI Image Contest, There’s Plenty of Beauty at the Bottom. Voting ends October 15th!

Most Stunning

SEM image of pollen

Lungs of Nature
Hanna Varga, Duke University

The image depicts particles from a dust sample collected on the California coast. This pair of pollen grains reminded the researcher of lungs.

Most Whimsical

SEM image

Dinos Take the City
James Loveless, NC State University

This sample is Gallium nitride grown on sapphire at very high temperatures. Remarkably, this surface was intended to be flat! At these extreme conditions, the crystal growth is often three-dimensional, and we discovered a city-like landscape of thin crystalline microstructures. I thought the dust particles looked like monsters akin to Godzilla, so I added a helicopter to help protect the city.

Most Unique Capability

Our Cups Floweth Over
Greg Allion and Sravanthi Vallabhuneni, NC State University

Thick photo resist sculpted by utilizing light diffraction and image reversal. The visual beauty speaks for itself. Structures like these can be used to make super hydrophobic surfaces.

New Phosphorus Sustainability Center Engages NNCI Scientists

NSF recently announced the 2021 class of Science and Technology Centers. This cohort includes six new Centers focused on a range of topics from optoelectronics to ice exploration. One of these Centers is led by RTNN Director Jacob Jones. With collaborators at RTNN, SENIC, and NCI-SW, Jones established the Science and Technologies for Phosphorus Sustainability (STEPS) Center which aims to reduce phosphorus dependence and its downstream effects on the environment. The origin of STEPS can be traced back to a 2016 Nanotechnology Signature Initiative and a series of RTNN-supported events that seeded several collaborative projects including a GRIP Award focused on using nanotechnology for water sustainability. Find out more about STEPS on the Center website and NC State press release.