(6ju) Functional 2D Material Nanoarchitectures for Sustainable Energy Generation

Sanjay K. Behura

Research Assistant Professor in Chemical Engineering, University of Illinois at Chicago, IL

E-Mail: sbehura1@uic.edu; Website: https://sanjaybehura.weebly.com/

Research Background:

The quantum confinement of charge carriers in two-dimensional (2D) crystals evolve new and, in several cases, superior electronic and optical properties with applicability in energy conversion, nano-optoelectronics, and nano-bio electronics. The challenge is how to controllably nucleate 2D crystals and their quantum heterostructures for engineered properties and advanced device functionality. Owing to the Van Hove singularity in the electronic density of states, the 2D semiconductors exhibit strong light-matter interactions. This enables 2D semiconductors to be surface-coupled with several other material systems including direct or indirect, narrow or wide bandgap inorganic and organic semiconductors to create new energy conversion avenues. For the past 8.5 years of my doctoral and post-doctoral training and research assistant professorship positions, I have built a solid foundation by addressing these multitude of challenging questions.

My graduate research was a result of research exposure from three countries with two scholarships including Commonwealth scholarship for doctoral exchange research at The University of Saskatchewan, Canada and second one is a Department of Science and Technology sponsored travel grant for Ph.D. summer school on ‘challenges in 2D materials’ at Technical University of Denmark. In the group of Prof. Qiaoqin Yang at The University of Saskatchewan, Canada, I primarily focused on developing strategies for synthesis of vertical graphene films with enhanced electron field emission characteristics. I have developed a novel strategy to produce high-aspect-ratio silicon nanowires directly on SiO₂/Si surfaces via oxidation and reduction in hydrogen environment. These nanowires exhibited quantum confinement effect as confirmed by Raman vibrational spectroscopic analysis.

My postdoctoral research with Prof. Vikas Berry at The University of Illinois at Chicago (UIC) involved nanoscale designing and bottom-up synthesis of 2D material heterostructures for low-temperature quantum transport and atomically-precise Moiré fringes. Currently the quantum heterostructures are assembled by transferring the 2D crystals produced on transition metal catalytic surfaces. These polymer-assisted transfer approaches introduce scattering centers for charge carrier transport and mis-orientation of 2D crystals. To address this challenge, I have developed novel surface-chemical-interaction chemistry to nucleate graphene, hexagonal boron nitride (h-BN) and their heterostructures directly on oxide and nitride-based gate-dielectric substrates and investigated low-temperature quantum transport phenomena and Moiré patterns of graphene and h-BN. I have also developed mechanistic understanding of epitaxial graphene formation with ultra-high Raman I_2D/I_G ratio on Co (111) surfaces.

In my current role as Research Assistant Professor at UIC, I am developing an ‘Emerging Nano-Photovoltaics Research Program on Mixed-Dimensional Junctions’. As Principal Investigator, I have recently received a research grant of US$ 100,000 and invited to write a commentary article in Nature Photonics on this emerging area of nano-energy research program. Being nominated as a graduate faculty, I am advising graduate thesis and undergraduate student projects. In collaboration with Dr. Anirudha Sumant of Center for Nanoscale Materials at Argonne National Laboratory, I am currently investigating an exciting project on the role of nanocrystalline diamond as an electron blocking inter-layer in graphene photovoltaic sensors. This collaboration also resulted a DOE user research proposal at Centre for Nanoscale Materials, Argonne National Laboratory. For the past 8.5 years, I have mentored 15 M.S. and B.S. student projects on 2D materials science and nanoscale photovoltaics which led to several peer-reviewed publications.

Research Interests:

With a solid foundation in the nanoscience of low-dimensional electronic materials and nanoengineering of energy materials and conversion, research projects with high possible throughput are being targeted. My goal is to establish an independent and self-sustaining research program on ‘mixed-dimensional complex nanoarchitectures’ for (i) surface-junction based emerging nano-photovoltaics, (ii) exciton physics, charge carrier transport, and recombination dynamics for advanced optoelectronics, and (iii) Fermi-level and band-gap engineering via chemical, electrical, and biological coupling. Towards achieving my research targets, I aim in developing two major projects in my new lab: (A) New 2D Material Heterostructures and Quantum Electronics: mechanistic understanding of growth chemistry for 1-atom, 2-atom, and 3-atom (soon 4 and 5-atom) thick inorganic 2D materials, their complex heterostructures, fundamental structure-property correlations, and low-temperature quantum transport phenomena and (B) Sustainable Energy Generations: mixed-dimensional emerging heterojunction nano-photovoltaics.

Teaching Interests:

The broad prospective of my research interests are further shaped by my recent teaching experiences. At UIC, I have developed an advanced nanoscience course ‘Graphene and Two-Dimensional (2D) Materials (ChE 494)’ from Spring 2017 and continue teaching in Fall 2017 and Spring 2018. In this course, I have employed both knowledge-centered (lectures about 2D concepts) and learning-centered (2D laboratory, group collaborations in mini-2D-symposium and science video preparation) techniques to ensure long-term retention of fundamental concepts. Total of 60 graduate and undergraduate students are trained on emerging 2D materials theory, processing and applications. The learning goals are: 2D materials science, synthesis chemistry, nanoscale characterizations, and advanced device functionality. Practical demonstration of concepts is a critical part of active learning and deep understanding, therefore, I included laboratory works: bottom-up synthesis of graphene, its chemical transfer, and Raman spectroscopic characterizations. To inculcate the idea of collaborations among students, I organize mini-symposium and give homework on making innovative science video, where students must interact with fellow students and present as a team. For Spring 2017, the overall teaching rating for this course is 5.00/5.00, which motivated me to further enrich the course program. For Spring 2018, I am selected to teach ‘Science and Technology of Graphene and 2D Materials (Hon 201)’ for UIC Honors College. As a new faculty, along with the above course, I will be teaching new courses on: ‘Materials for Energy’ and ‘Engineering Solar Cells at the Nanoscale’. For the past 8.5 years, I have delivered 10 invited lectures and 20 contributed talks at various institutions/conferences in USA, Denmark, Canada, and India. I have presented an invited talk on ‘2D heterostructure nano-optoelectronics' at 2017 MRS Fall Meeting, Boston in the 'Symposium NM02-Anisotropic Carbon Nanomaterials-Frontiers in Basic and Applied Research'. The invited lectures afforded me the opportunity to further sharpen my teaching skills in front of the broad and diverse audience.

Future Direction:

As an independent investigator, I would like to continue the idea of using experimental techniques and theoretical analysis to understand the structure-property correlations and diverse functionalities of 2D materials and their nanoscale attributes. In this regard, I believe the functional 2D material system I am currently focusing provides a rich experimental toolbox, with a number of fascinating and currently unexplored phenomena to reconnoiter. Potential and immediate future plan includes: (i) mechanistic understanding of charge transport at the interface of biological entities and 2D materials for bio-photovoltaics; (ii) Interfacing of 2D layers with perovskites for novel photojunctions; (iii) origami and kirigami of 2D nanocomposites and device functionality.

The distinctiveness of my methodology is the ability to develop complex 2D heterostructure circuits, characterize their structure-property correlations, and design novel energy junctions via nano-bio interfacing. Due to the highly interdisciplinary nature of my work, I envision a strong and active collaboration with fellow faculty in the university to setup specific techniques in my lab.

Selected Publications (6 out of 35 Publications; 280 Citations; *Corresponding Author):

1. K. Behura*, C. Wang, Y. Wen, and V. Berry*, “Graphene/semiconductor heterojunction sheds light on emerging photovoltaics,” Nature Photonics, Under 2nd Revision (2018).
2. K. Behura, P. Nguyen, R. Debbarma, S. Che, M. R. Seacrist, and V. Berry, “Chemical interaction-guided, metal-free growth of large-area hexagonal boron nitride on silicon-based substrates,” ACS Nano, Vol. 11, p. 4985-4994 (2017). Highlighted in Nature India.
3. K. Behura, P. Nguyen, S. Che, R. Debbarma, and V. Berry, “Large-area, transfer-free oxide-assisted synthesis of hexagonal boron nitride films and their heterostructures with MoS₂ and WS₂,” Journal of the American Chemical Society, Vol. 137, p. 13060-13065 (2015).
4. K. Behura and V. Berry, “Interfacial nondegenerate doping of MoS₂ and other two-dimensional semiconductors,” ACS Nano, Vol. 9, p. 2227-2230 (2015).
5. K. Behura*, S. Nayak, I. Mukhopadhyay, and O. Jani, “Junction characteristics of chemically-derived graphene/p-Si heterojunction solar cell,” Carbon, Vol. 67, p. 766-774 (2014).
6. Nguyen^#, S. K. Behura^#, M. R. Seacrist, and V. Berry, “Intergrain diffusion of carbon radical for wafer-scale, direct growth of graphene on silicon-based dielectrics,” ACS Applied Materials and Interfaces, DOI: 10.1021/acsami.8b07655 (2018). (^#Authors with Equal Contributions)

Selected Patents (2 out of 10 invention disclosures):

“Epitaxial growth of defect-free, wafer-scale single-layer graphene on cobalt,” V. Berry, S. K. Behura, P. Nguyen, and M. R. Seacrist, WO2017058928A1, Priority Date: Oct. 1, 2015, Publication Date: Apr. 6, 2017.

“Direct formation of hexagonal boron nitride on Si-based dielectrics,” V. Berry, S. K. Behura, P. Nguyen, and M. R. Seacrist, WO2017196559A1, Priority Date: May 12, 2016, Publication Date: Nov. 16, 2017.