Timothy P. Bender
Professor, Associate Chair Undergraduate Studies
Department of Chemical Engineering and Applied Chemistry
University of Toronto
“Boron subphthalocyanines and subnaphthalocyanines for organic photovoltaics: their ambient stability, the influence of halogens, the mixed alloys, their sustainability, and using computational modeling to accelerate their development“
For some time, our grouphas been focused on the design, synthesis and application of derivatives ofboron subphthalocyanines (BsubPcs), a macrocyclic molecule with a central chelated boron atom. Our focal point has been and continues to beequally balanced between the basic and applied chemistry of BsubPcs, and theirapplication as light harvesting and electronic conducting materials in organicphotovoltaics (OPVs)/solar cells (OSCs).
Forthis presentation I will outline how we have developed BsubPcs for theirapplication in OPVs and other organic electronic devices. For OPVs, we have formeda tactic to their progress whereby taking on their basic and applied chemistryis justified by a development cycle (Figure) which includes their physicalchemistry and characterization, their immediate integration into OPVs and basedon their indoor stability placing the OPVs in the ambient environment to evaluatetheir stability. This data acquisition cycle feeds back into their moleculardesign with is also accelerated through a computational model. This tactic isin place to truly develop their ultimate application in OPVs.
Forthis presentation I will highlight the development of BsubPcs for OPVs, notingseveral points: the influence of peripheral halogenations; three types of OPVdevice architectures we have explored; the influence of solvents on theirnano-structures on solution casting for device; etc.
Inaddition to BsubPcs, we have taken an equal approach to extended p-conjugated derivativescalled boron subnaphthalocyanines (BsubNcs); BsubNcs also being unique andbeneficial materials for OPV application as they extend the solar absorptionspectrum when coupled with BsubPcs. We have shown that BsubNcs actually becomerandomly chlorinated during their synthetic preparation and actually then form amixed alloy composition of chlorinated materials, which we have designated asCl-ClnBsubNcs. The mixed alloy composition is unique, and has beendetermined to be a mixture of 24 (more or less) chlorinated BsubNcs. Despitebeing a mixture 24 or more BsubNcs form uniquely single crystals. The formationof single crystals is enabled by the chlorine atoms occupying vacancies withinthe solid state structure, the vacancies being the so-called “bay position” ofthe BsubNcs structure. During this presentation I will highlight how odd themixed alloy composition of organic materials is and how hard it has been toseparate the mixed alloyed composition. I will also highlight how we are movingforward with making mixed alloyed compositions of BsubPcs fully justified bythe potential performance increase in OPVs.
Integratedinto this data acquisition cycle is a computational modeling methodology thatis used to screen potential BsubPcs and BsubNcs for their application in OPVs.I will highlight how the computational model justified the time and resourcecommitment to their synthesis and development.
Mostrecently we have identified a pathway to BsubPcs whereby all carbons arebio-sourced. So I will also highlight in this presentation the sustainabilityof BsubPcs for then justifying their application into OPVs.
Co-authors/investigatorswill be identified during this presentation.
Some Relevant References.
 “Outdoor Performance andStability of Boron Subphthalocyanines Applied as Electron Acceptors inFullerene-Free Organic Photovoltaics.” Josey, D.; et al, ACS Energy Lett., 2017, 2(3),726-732. DOI: 10.1021/acsenergylett.6b00716.
 “Boron Subphthalocyaninesas Electron Donors in Outdoor Lifetime Monitored Organic Photovoltaic Cells.”Garner, R.K.; et al, Solar EnergyMaterials and Solar Cells, 2018 176, 331-335. DOI:10.1016/j.solmat.2017.10.018
 “8.4% efficient fullerene-freeorganic solar cells exploiting long-range exciton energy transfer” Cnops, K.;et al., Nature Comm., 5, Articlenumber: 3406, DOI:10.1038/ncomms4406.
 “The mixed and alloyed chemicalcomposition of chloro-(chloro)n-boron subnaphthalocyanines dictates theirphysical properties and performance in organic photovoltaics.” Dang, J.D.; etal, J. Mat. Chem. A., 2016, 4,9566-9577. DOI: 10.1039/C6TA02457B
 “Phenoxy-(chloro)n-boronsubnaphthalocyanines; alloyed mixture, electron-accepting functionality,enhanced solubility for bulk heterojunction organic photovoltaics” Dang, J.D.;et al, ACS Omega, 2018, 3(2), 2093-2103. DOI: 10.1021/acsomega.7b01892.
“The Mixed Alloyed Chemical Compositionof Chloro-(chloro)n-Boron Subnaphthalocyanines Dictates Their Performance asElectron-Donating and Hole-Transporting Materials in Organic Photovoltaics”Garner, R.K.; et al, ACS Appl. EnergyMaterials, 2017, 1(3), 1029-1036.DOI: 10.1021/acsaem.7b00180.
 “OutdoorStability of Chloro-(Chloro)n-Boron Subnaphthalocyanine and Chloro-BoronSubphthalocyanine as Electron Acceptors in Bilayer and Trilayer OrganicPhotovoltaics” Josey, D.; et al, ACSApplied Energy Materials, 2019, 2(2),979-986. DOI:10.1021/acsaem.8b01918
 “Enhanced Analytical and Physical Characterizationof Mixtures of Random Bay-Position Brominated Boron Subnaphthalocyanines Enabledby Establishing a Partial Separation Method” Holst, D.; et al, New J. Chem.,2021, Advance Article.