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Title: Crystalline Nanoporous Frameworks: a Nanolaboratory for Probing Excitonic Device Concepts.

Abstract

Electro-optical organic materials hold great promise for the development of high-efficiency devices based on exciton formation and dissociation, such as organic photovoltaics (OPV) and organic light-emitting devices (OLEDs). However, the external quantum efficiency (EQE) of both OPV and OLEDs must be improved to make these technologies economical. Efficiency rolloff in OLEDs and inability to control morphology at key OPV interfaces both reduce EQE. Only by creating materials that allow manipulation and control of the intimate assembly and communication between various nanoscale excitonic components can we hope to first understand and then engineer the system to allow these materials to reach their potential. The aims of this proposal are to: 1) develop a paradigm-changing platform for probing excitonic processes composed of Crystalline Nanoporous Frameworks (CNFs) infiltrated with secondary materials (such as a complimentary semiconductor); 2) use them to probe fundamental aspects of excitonic processes; and 3) create prototype OPVs and OLEDs using infiltrated CNF as active device components. These functional platforms will allow detailed control of key interactions at the nanoscale, overcoming the disorder and limited synthetic control inherent in conventional organic materials. CNFs are revolutionary inorganic-organic hybrid materials boasting unmatched synthetic flexibility that allow tuning of chemical, geometric, electrical, andmore » light absorption/generation properties. For example, bandgap engineering is feasible and polyaromatic linkers provide tunable photon antennae; rigid 1-5 nm pores provide an oriented, intimate host for triplet emitters (to improve light emission in OLEDs) or secondary semiconducting polymers (creating a charge-separation interface in OPV). These atomically engineered, ordered structures will enable critical fundamental questions to be answered concerning charge transport, nanoscale interfaces, and exciton behavior that are inaccessible in disordered systems. Implementing this concept also creates entirely new dimensions for device fabrication that could both improve performance, increase durability, and reduce costs with unprecedented control of over properties. This report summarizes the key results of this project and is divided into sections based on publications that resulted from the work. We begin in Section 2 with an investigation of light harvesting and energy transfer in a MOF infiltrated with donor and acceptor molecules of the type typically used in OPV devices (thiophenes and fullerenes, respectively). The results show that MOFs can provide multiple functions: as a light harvester, as a stabilizer and organizer or the infiltrated molecules, and as a facilitator of energy transfer. Section 3 describes computational design of MOF linker groups to accomplish light harvesting in the visible and facilitate charge separation and transport. The predictions were validated by UV-visible absorption spectroscopy, demonstrating that rational design of MOFs for light-harvesting purposes is feasible. Section 4 extends the infiltration concept discussed in Section to, which we now designate as "Molecule@MOF" to create an electrically conducting framework. The tailorability and high conductivity of this material are unprecedented, meriting publication in the journal Science and spawning several Technical Advances. Section 5 discusses processes we developed for depositing MOFs as thin films on substrates, a critical enabling technology for fabricating MOF-based electronic devices. Finally, in Section 6 we summarize results showing that a MOF thin film can be used as a sensitizer in a DSSC, demonstrating that MOFs can serve as active layers in excitonic devices. Overall, this project provides several crucial proofs-of- concept that the potential of MOFs for use in optoelectronic devices that we predicted several years ago [ 3 ] can be realized in practice.« less

Authors:
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Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1159322
Report Number(s):
SAND2014-18260
537875
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Allendorf, Mark D., Azoulay, Jason, Ford, Alexandra Caroline, Foster, Michael E., El Gabaly Marquez, Farid, Leonard, Francois Leonard, Leong-Hau, Kirsty, Stavila, Vitalie, Talin, Albert Alec, Wong, Brian M., Brumbach, Michael T., Van Gough, D., Lambert, Timothy N., Rodriguez, Mark A., Spoerke, Erik David, Wheeler, David Roger, Deaton, Joseph C., Centrone, Andrea, Haney, Paul, Kinney, R., Szalai, Veronika, and Yoon, Heayoung P. Crystalline Nanoporous Frameworks: a Nanolaboratory for Probing Excitonic Device Concepts.. United States: N. p., 2014. Web. doi:10.2172/1159322.
Allendorf, Mark D., Azoulay, Jason, Ford, Alexandra Caroline, Foster, Michael E., El Gabaly Marquez, Farid, Leonard, Francois Leonard, Leong-Hau, Kirsty, Stavila, Vitalie, Talin, Albert Alec, Wong, Brian M., Brumbach, Michael T., Van Gough, D., Lambert, Timothy N., Rodriguez, Mark A., Spoerke, Erik David, Wheeler, David Roger, Deaton, Joseph C., Centrone, Andrea, Haney, Paul, Kinney, R., Szalai, Veronika, & Yoon, Heayoung P. Crystalline Nanoporous Frameworks: a Nanolaboratory for Probing Excitonic Device Concepts.. United States. https://doi.org/10.2172/1159322
Allendorf, Mark D., Azoulay, Jason, Ford, Alexandra Caroline, Foster, Michael E., El Gabaly Marquez, Farid, Leonard, Francois Leonard, Leong-Hau, Kirsty, Stavila, Vitalie, Talin, Albert Alec, Wong, Brian M., Brumbach, Michael T., Van Gough, D., Lambert, Timothy N., Rodriguez, Mark A., Spoerke, Erik David, Wheeler, David Roger, Deaton, Joseph C., Centrone, Andrea, Haney, Paul, Kinney, R., Szalai, Veronika, and Yoon, Heayoung P. 2014. "Crystalline Nanoporous Frameworks: a Nanolaboratory for Probing Excitonic Device Concepts.". United States. https://doi.org/10.2172/1159322. https://www.osti.gov/servlets/purl/1159322.
@article{osti_1159322,
title = {Crystalline Nanoporous Frameworks: a Nanolaboratory for Probing Excitonic Device Concepts.},
author = {Allendorf, Mark D. and Azoulay, Jason and Ford, Alexandra Caroline and Foster, Michael E. and El Gabaly Marquez, Farid and Leonard, Francois Leonard and Leong-Hau, Kirsty and Stavila, Vitalie and Talin, Albert Alec and Wong, Brian M. and Brumbach, Michael T. and Van Gough, D. and Lambert, Timothy N. and Rodriguez, Mark A. and Spoerke, Erik David and Wheeler, David Roger and Deaton, Joseph C. and Centrone, Andrea and Haney, Paul and Kinney, R. and Szalai, Veronika and Yoon, Heayoung P.},
abstractNote = {Electro-optical organic materials hold great promise for the development of high-efficiency devices based on exciton formation and dissociation, such as organic photovoltaics (OPV) and organic light-emitting devices (OLEDs). However, the external quantum efficiency (EQE) of both OPV and OLEDs must be improved to make these technologies economical. Efficiency rolloff in OLEDs and inability to control morphology at key OPV interfaces both reduce EQE. Only by creating materials that allow manipulation and control of the intimate assembly and communication between various nanoscale excitonic components can we hope to first understand and then engineer the system to allow these materials to reach their potential. The aims of this proposal are to: 1) develop a paradigm-changing platform for probing excitonic processes composed of Crystalline Nanoporous Frameworks (CNFs) infiltrated with secondary materials (such as a complimentary semiconductor); 2) use them to probe fundamental aspects of excitonic processes; and 3) create prototype OPVs and OLEDs using infiltrated CNF as active device components. These functional platforms will allow detailed control of key interactions at the nanoscale, overcoming the disorder and limited synthetic control inherent in conventional organic materials. CNFs are revolutionary inorganic-organic hybrid materials boasting unmatched synthetic flexibility that allow tuning of chemical, geometric, electrical, and light absorption/generation properties. For example, bandgap engineering is feasible and polyaromatic linkers provide tunable photon antennae; rigid 1-5 nm pores provide an oriented, intimate host for triplet emitters (to improve light emission in OLEDs) or secondary semiconducting polymers (creating a charge-separation interface in OPV). These atomically engineered, ordered structures will enable critical fundamental questions to be answered concerning charge transport, nanoscale interfaces, and exciton behavior that are inaccessible in disordered systems. Implementing this concept also creates entirely new dimensions for device fabrication that could both improve performance, increase durability, and reduce costs with unprecedented control of over properties. This report summarizes the key results of this project and is divided into sections based on publications that resulted from the work. We begin in Section 2 with an investigation of light harvesting and energy transfer in a MOF infiltrated with donor and acceptor molecules of the type typically used in OPV devices (thiophenes and fullerenes, respectively). The results show that MOFs can provide multiple functions: as a light harvester, as a stabilizer and organizer or the infiltrated molecules, and as a facilitator of energy transfer. Section 3 describes computational design of MOF linker groups to accomplish light harvesting in the visible and facilitate charge separation and transport. The predictions were validated by UV-visible absorption spectroscopy, demonstrating that rational design of MOFs for light-harvesting purposes is feasible. Section 4 extends the infiltration concept discussed in Section to, which we now designate as "Molecule@MOF" to create an electrically conducting framework. The tailorability and high conductivity of this material are unprecedented, meriting publication in the journal Science and spawning several Technical Advances. Section 5 discusses processes we developed for depositing MOFs as thin films on substrates, a critical enabling technology for fabricating MOF-based electronic devices. Finally, in Section 6 we summarize results showing that a MOF thin film can be used as a sensitizer in a DSSC, demonstrating that MOFs can serve as active layers in excitonic devices. Overall, this project provides several crucial proofs-of- concept that the potential of MOFs for use in optoelectronic devices that we predicted several years ago [ 3 ] can be realized in practice.},
doi = {10.2172/1159322},
url = {https://www.osti.gov/biblio/1159322}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}