Prof. Brendan T. O'Connor Profile

Prof. Brendan T. O'Connor

Associate Professor at North Carolina State Univ

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Author

Publications (15)

SPIE Journal Paper | 21 July 2022

Cephalopod-inspired snapshot multispectral sensor based on geometric phase lens and stacked organic photodetectors

Ali Altaqui, Harry Schrickx, Sydney Gyurek, Pratik Sen, Michael Escuti, Brendan O'Connor, Michael Kudenov

OE, Vol. 61, Issue 07, 077104, (July 2022) https://doi.org/10.1117/12.10.1117/1.OE.61.7.077104

KEYWORDS: Sensors, Diffraction, Multispectral imaging, Optical engineering, Point spread functions, Eye, Polarization, Optical filters, Multispectral sensing, Chromatic aberrations

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Proceedings Article | 4 August 2021 Presentation

Thermal relaxations in polymer semiconductors and the impact on organic solar cell stability

Brendan O'Connor

Proceedings Volume 11809, 118090E (2021) https://doi.org/10.1117/12.2596163

KEYWORDS: Polymers, Solar cells, Organic photovoltaics, Semiconductors, Polymer thin films, Molecules, Organic semiconductors, Glasses

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Proceedings Article | 4 August 2021 Presentation

Balancing crop production and energy harvesting in organic solar-powered greenhouses

Eshwar Ravishankar, Ronald Booth, Harald Ade, Heike Sederoff, Brendan O'Connor

Proceedings Volume 11809, 118090R (2021) https://doi.org/10.1117/12.2595764

KEYWORDS: Atmospheric modeling, Solar energy, Agriculture, Transmittance, Solar cells, Performance modeling, Organic photovoltaics, Light sources and illumination, Energy efficiency, Computational modeling

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Proceedings Article | 20 August 2020 Presentation

ITO-free fully solution-processed flexible semi-transparent organic photovoltaics utilizing metal nanowire for anode and cathode

Ronald Booth, Yuan Xiong, Yuxuan Liu, Yong Zhu, Harald Ade, Brendan O'Connor

Proceedings Volume 11474, 1147410 (2020) https://doi.org/10.1117/12.2570470

KEYWORDS: Metals, Electrodes, Organic photovoltaics, Nanowires, Solar energy, Indium, Tin, Oxides, Opacity, Silver

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SPIE Journal Paper | 25 February 2020

Optimization of an intrinsic coincident polarimeter and quantitative architectural comparison of different polarimeter techniques

Ruonan Yang, Pratik Sen, Brendan O'Connor, Michael Kudenov

OE, Vol. 59, Issue 02, 024111, (February 2020) https://doi.org/10.1117/12.10.1117/1.OE.59.2.024111

KEYWORDS: Polarimetry, Signal to noise ratio, Wave plates, Interference (communication), Optical engineering, Sensors, Polarization, Optical spheres, Spatial resolution, Electrodes

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Proceedings Article | 10 September 2019 Presentation

Sequential deposition of organic films with eco-compatible solvents enables high-efficiency nonfullerene solar cells (Conference Presentation)

Long Ye, Yuan Xiong, Zheng Chen, Qianqian Zhang, Reece Henry, Brendan O'Connor, Wei You, Harald Ade

Proceedings Volume 11094, 110940O (2019) https://doi.org/10.1117/12.2529802

KEYWORDS: Solar cells, Polymers, Polymer thin films, Thin film devices, Organic photovoltaics, Molecules, Crystals, Instrument modeling, Performance modeling, X-rays

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Casting of a donor:acceptor bulk-heterojunction structure from a single ink has been the predominant fabrication method of solution-processed organic photovoltaics (OPVs). Despite the success of such bulk-heterojunction, the task of controlling its microstructure in a single casting process has been challenging and arduous and alternative approaches are desired. To achieve and even improve OPVs with a desirable microstructure, a facile and eco-compatible sequential deposition approach is demonstrated for nonfullerene polymer/small molecule pairs. Using a known weakly crystalline polymer FTAZ as the model material, we show the profound influence of casting solvent on the molecular ordering of the film, and thus the device performance and mesoscale morphology of sequentially deposited OPVs can be tuned[1]. Static and in-situ X-ray scattering indicate that applying the green solvent limonene is able to greatly promote the molecular order of FTAZ and form the largest domain spacing exclusively, which correlate well with the best efficiency in sequentially deposited devices. The sequentially cast device generally outperforms its control device[2] based on traditional single-ink bulk-heterojunction structure. Investigations of distinct material systems suggest that our approach be applicable to many conjugated polymers and nonfullerene acceptors, which yield consistently higher fill factors than traditional bulk-heterojunction devices. Moreover, the relationships between polymer:solvent interactions, thin-film microstructure, and device performance are discussed for these sequentially deposited devices. It is noted that polymer:solvent interaction parameter χ positively correlates with domain spacing in the devices. Our findings shed light on innovative approaches to rationally create ink-stable, environmentally friendly, and highly efficient nonfullerene solar cells. Reference [1] Ye, L.; Xiong, Y.; Chen, Z.; Zhang, Q.; Fei, Z.; Henry, R.; Heeney, M.; O’Connor, B.; You, W.; Ade, H. Adv. Mater. 2019, under review. [2] Ye, L.; Xiong, Y.; Zhang, Q.; Li, S.; Wang, C.; Jiang, Z.; Hou, J.; You, W.; Ade, H. Adv. Mater. 2018, DOI: 10.1002/adma.201705485.

Proceedings Article | 10 September 2019 Presentation

Semi-transparent organic solar cells for greenhouse application (Conference Presentation)

Yuan Xiong, Eshwar Ravishankar, Jennifer Swift, Harald Ade, Ronald Booth, Melodi Charles, Reece Henry, Brendan O'Connor, Jeromy Rech, Carole Saravitz, Heike Sederoff, Long Ye, Wei You

Proceedings Volume 11094, 110940N (2019) https://doi.org/10.1117/12.2529997

KEYWORDS: Organic photovoltaics, Solar cells, Botany, Physics, Carbon, Electronics, Aerospace engineering, Biology, Chemistry, Photovoltaics

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Semi-transparent Organic Solar Cells for Greenhouse Application Yuan Xiong1*, Eshwar Ravishankar2, Jennifer Swift3, Harald Ade1*, Ronald Booth2, Melodi Charles4, Reece Henry1, Brendan O’Connor2, Jeromy James Rech5, Carole Saravitz3, Heike Sederoff4, Long Ye1, Wei You5 1. Department of Physics, Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, NC 27695, USA 2. Department of Mechanical and Aerospace Engineering and ORaCEL, North Carolina State University, Raleigh, NC 27695, USA 3. Department of Plant Biology, North Carolina State University, Raleigh, NC 27695, USA 4. Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA 5. Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA E-mail: yxiong8@ncsu.edu; hwade@ncsu.edu Semitransparent organic solar cells (ST-OSCs) show great potential in building-integrated photovoltaics due to the advantages in solution processability, flexibility, and transparency. Herein, we present a systematic study on the application of high-performance ST-OSC filters in a greenhouse by utilizing three representative systems with different spectral responses, namely, FTAZ:PC71BM[1], FTAZ:IT-M[2, 3], and PTB7-Th:IEICO-4F[4]. Specifically, the cultivation of red leaf lettuce is conducted in a controlled environment growth chamber, which is possible to duplicate any climate, and under different ST-OSC filters. In principle, the ST-OSCs absorb a portion of the solar spectrum for power generation and lettuce utilizes the penetrated light for photosynthesis. Furthermore, we quantitatively investigate the leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared ST-OSC filters treatments. On the base of statistical analysis after the growth cycle, we can identify the best ST-OSC for plant growth. These results thus pave the way to integrate ST-OSCs with greenhouses. [1] S. C. Price, A. C. Stuart, L. Yang, H. Zhou, W. You, Journal of the American Chemical Society 2011, 133, 4625. [2] L. Ye, Y. Xiong, Q. Zhang, S. Li, C. Wang, Z. Jiang, J. Hou, W. You, H. Ade, Advanced Materials 2018, 30, 1705485. [3] Y. Xiong, L. Ye, A. Gadisa, Q. Zhang, J. J. Rech, W. You, H. Ade, Advanced Functional Materials 2019, 29, 1806262. [4] X. Song, N. Gasparini, L. Ye, H. Yao, J. Hou, H. Ade, D. Baran, ACS Energy Letters 2018, 3, 669.

Proceedings Article | 10 September 2019 Presentation

Rational strategies to stabilize the morphology of non-fullerene organic solar cells (Conference Presentation)

Huawei Hu, Long Ye, Masoud Ghasemi, Nrup Balar, Jeromy Rech, Wei You, Samuel Stuard, Brendan O'Connor, Harald Ade

Proceedings Volume 11094, 1109410 (2019) https://doi.org/10.1117/12.2529990

KEYWORDS: Organic photovoltaics, Solar cells, Solar energy, Mechanical efficiency, Polymers

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Proceedings Article | 18 September 2018 Presentation

Crystallization of non-fullerene acceptor might cause catastrophic failure in ductile organic solar cells (Conference Presentation)

Masoud Ghasemi, Huawei Hu, Nrup Balar, Brendan O'Connor, Harald Ade

Proceedings Volume 10737, 107370P (2018) https://doi.org/10.1117/12.2321996

KEYWORDS: Crystals, Solar cells, Organic photovoltaics, Polymers, Molecules, Lithium, Systems modeling, Fullerenes, Photovoltaics, Thermodynamics

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Organic solar cell (OSC) technology has recently achieved over 13% efficiency through the synthesis of novel non-fullerene small molecule acceptors (NFAs), which can be processed from benign solvents as low-cost third generation photovoltaics[1,2]. Of critical importance to OSCs is understanding the morphological and thermal stability of the active layers governed by thermodynamics and kinetics as an intrinsic stability process which cannot be controlled by encapsulation[3,4]. Here we highlight the importance of ductility of donor polymers on nucleation and growth of micro-size small molecule crystals which leads to the catastrophic failure of the solar cells in the long-term operating condition We consider three high performance polymers P3HT, PBnDBT-FTAZ, and PffBT4T-C9C13 blended with EH-IDTBR as the model systems to investigate the thermal stability of state of the art non-fullerene OSCs, where elevated temperatures were used to accelerate the crystal formation and imitate the long-term operation conditions of OCSs. We also propose an easy accessible method using differential scanning calorimetry (DSC) to investigate the thermal behavior of NFA in the blends. Although non-fullerene solar cells have shown to have better overall morphological stability compared to their fullerene counterparts, our results suggest that catastrophic failure due to micro-size crystal formation in non-fullerene systems can happen at a rate similar to fullerene systems unless the right donor polymer is chosen to suppress the crystallization of small molecule. It is also shown and argued that the growth rate of small molecule crystals can be reduced upon mixing of NFAs with semi-crystalline polymers, such as P3HT with a higher overall density compared to amorphous donor polymers, i.e. PBnDT-FTAZ. Our findings may pave a way to understand and predict the morphological stability of non-fullerene OSCs. References [1] L. Ye, Y. Xiong, Q. Zhang, S. Li, C. Wang, Z. Jiang, J. Hou, W. You, H. Ade, Adv. Mater. 2017, DOI: 10.1002/adma.201705485. [2] S. Holliday, R. S. Ashraf, A. Wadsworth, D. Baran, S. A. Yousaf, C. B. Nielsen, C.-H. Tan, S. D. Dimitrov, Z. Shang, N. Gasparini, M. Alamoudi, F. Laquai, C. J. Brabec, A. Salleo, J. R. Durrant, I. McCulloch, Nat. Commun. 2016, 7, 11585. [3] M. Ghasemi, L. Ye, Q. Zhang, L. Yan, J. H. Kim, O. Awartani, W. You, A. Gadisa, H. Ade, Adv. Mater. 2017, 29, 1604603. [4] L. Ye, H. Hu, M. Ghasemi, T. Wang, B. A. Collins, J.-H. Kim, K. Jiang, J. Carpenter, H. Li, Z. Li, T. McAfee, J. Zhao, X. K. Chen, J. Y. L. Lai, T. Ma, J.-L. Bredas, H. Yan, H. Ade, Nat. Mater. 2018, DOI: 10.1038/s41563-017-0005-1.

Proceedings Article | 18 September 2018 Presentation

Viscoelastic polymer semiconductors for stretchable electronics: the importance of interfaces on mechanical behavior (Conference Presentation)

Tianlei Sun, Runqiao Song, Nrup Balar, Brendan O'Connor

Proceedings Volume 10739, 1073907 (2018) https://doi.org/10.1117/12.2322023

KEYWORDS: Polymers, Semiconductors, Stretchable circuits, Interfaces, Field effect transistors, Sensors, Polymer thin films, Polymeric sensors, Surface roughness, Glasses

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Proceedings Article | 14 May 2018 Paper

Monolithic intrinsic coincident polarimeter using organic photovoltaics

Ruonan Yang, Pratik Sen, Brendan O'Connor, Michael Kudenov

Proceedings Volume 10655, 106550T (2018) https://doi.org/10.1117/12.2500476

KEYWORDS: Polarimetry, Polarization, Absorption, Calibration, Bismuth, Data modeling, Organic photovoltaics, Wave plates, Polymers, Free space

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Proceedings Article | 30 August 2017 Presentation + Paper

Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics and architectural comparison of polarimeter techniques

Ruonan Yang, Pratik Sen, B. O'Connor, M. Kudenov

Proceedings Volume 10407, 1040705 (2017) https://doi.org/10.1117/12.2273885

KEYWORDS: Polarimetry, Condition numbers, Signal to noise ratio, Organic photovoltaics, Imaging devices, Photovoltaics, Polymers, Radio optics, Wave plates, Modulation

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Proceedings Article | 5 October 2015 Presentation

Charge transport in highly aligned conjugated polymers (Presentation Recording)

Brendan O'Connor, Xiao Xue, Tianlei Sun

Proceedings Volume 9568, 95680U (2015) https://doi.org/10.1117/12.2187646

KEYWORDS: Polymers, Thin film devices, Transistors, Nanostructuring, Optical spectroscopy, Transmission electron microscopy, X-rays, Scattering, Molecular spectroscopy, Optical alignment

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Proceedings Article | 1 September 2015 Paper

Complete intrinsic coincident polarimetry using stacked organic photovoltaics

S. Gupta Roy, O. Awartani, P. Sen, B. O'Connor, M. Kudenov

Proceedings Volume 9613, 961308 (2015) https://doi.org/10.1117/12.2188972

KEYWORDS: Polarization, Polarimetry, Polymers, Calibration, Polymer thin films, Organic photovoltaics, Absorption, Spatial resolution, Wave plates, Measurement devices

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Proceedings Article | 7 February 2007 Paper

Cantilevers with integrated organic LEDs for scanning probe microscopy

Kwang Hyup An, Brendan O’Connor, Yiying Zhao, William Loh, Kevin Pipe, Max Shtein

Proceedings Volume 6470, 64700U (2007) https://doi.org/10.1117/12.700793

KEYWORDS: Organic light emitting diodes, Silicon, Near field scanning optical microscopy, Electrodes, Electroluminescence, Metals, Light sources, Scanning electron microscopy, Light emitting diodes, Semiconductors

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Showing 5 of 15 publications

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