Speaker: Brendon O’Connor, NCSU Mechanical and Aerospace Engineering

Brendon O’Connor, NCSU Mechanical and Aerospace Engineering, Organic Semiconductors for Advanced Sensing, Energy Harvesting, and Agriculture

Abstract:
Organic semiconductors have a number of unique properties that can be exploited to achieve electronic devices with functionalities not possible with traditional inorganic semiconductors. In this talk, I will highlight several applications enabled by these unique materials. To start I will discuss the ability to achieve net-zero energy (NZE) greenhouses through the integration of semitransparent organic solar cells (OSCs). Greenhouses vastly increase agricultural land-use
efficiency. However, they also consume significantly more energy than conventional farming due in-part to conditioning the greenhouse space. One way to mitigate the increase in energy consumption is to integrate solar modules onto the greenhouse structure. Semitransparent organic solar cells (OSCs) are particularly attractive given that their spectral absorption can be tuned to minimize the attenuation of sunlight over the plants photosynthetically active spectrum. We show through detailed energy balance modeling that OSC integration can achieve NZE greenhouses. We also show that plant growth under OSC filters is not significantly hindered. Future directions in a new controlled environment agriculture paradigm will then be discussed. The talk will then turn to advanced polarimetric imaging and hyperspectral imaging enabled by organic semiconductors. We show that uniaxial aligning polymer semiconductors in the plane of the film induces significant dichroism. When these oriented films are applied in photodetectors that have intrinsic polarization sensitivity. By stacking several polarized detectors along the same
optical axis we show that the full polarization state of light can be realized. These devices also enable a novel strategy for hyperspectral imaging. Lastly, the talk will turn to achieving mechanically robust flexible and stretchable organic electronics. Stretchable devices have the potential to advance soft-robotics, wearables, and bio-integrated electronics. Here we focus on the fundamental thermomechanical behavior of polymer semiconductors measured through
dynamic mechanical analysis and the implication of the mechanical relaxation on high-performance stretchable devices.

Bio:
Dr. Brendan O’Connor is currently an Associate Professor in the Mechanical and Aerospace Engineering Department at NC State University. He received his PhD from the University of Michigan in Mechanical Engineering in 2009. He was then a NRC-NIST postdoctoral fellow at the National Institute of Standards and Technology (NIST) in the polymers division. He then joined NC State in 2011. He is a recipient of an NSF CAREER award and was named a University Faculty Scholar in 2018.