(Invited) Boron Subphthalocyanines, Boron Subnaphthalocyanines and Silicon Phthalocyanines - All Very Versatile Materials for Organic Photovoltaics
Authors: Bender Timothy P 
Published: February 2020

For some time, our group has been focused on the design and synthesis of derivatives of boron subphthalocyanine (BsubPc) for application in organic electronics with a specific focus on organic photovoltaics and light emitting diodes; during this presentation however I will focus specifically on their application in organic photovoltaics.  I will begin by focusing on our efforts with regards to synthetic variants of BsubPcs and their application in planar heterojunction organic photovoltaic cells (OPVs, organic solar cells, OSCs).  After summarizing this work, I will then outline our very recent results where we took BsubPc based planar heterojunction organic photovoltaic cells and put them in the ambient environment on the roof of our building in downtown Toronto during the summer of 2015.  What we found was that during that time, the BsubPc based cells were remarkably stable.  We were able to form a structure property relationship to their stability in the ambient environment.  Recently, we have also shown that BsubPcs are deficient triplet harvesters from pentacene.  They are amongst only a few materials known to facilitate this process.

In parallel we have also been exploring the concept of complementary absorption engineering by either the chemical modification of BsubPcs or by pairing BsubPcs with alternative materials having complementary absorption profiles.  For example, we have shown that a highly substituted BsubPc can yield a red shifted absorption profile of approximately 100 nm.  This shift is equivalent to that of boron subnaphthalocyanines (BsubNcs). We have also recently been exploring the chemistry of BsubNcs. I will outline our results and the application of our BsubNcs in OPVs.[1] Time permitting, I will also outline the pairing of a BsubPc with phosphorus tetrabenzotriazacorrole [a phthalocyanine analogue] which yielded a unique gray organic photovoltaic cell and our group’s recent exploration of the bulk-heterojunction OPV space whereby BsubPcs are fullerene alternatives, although we are not the first to do so.[2]

Finally, during last year’s meeting, I outlined how our group’s recent exploration of other p-block metal phthalocyanines (Pcs) including Pcs of aluminum, silicon, germanium and phosphorous yielded the conclusion that silicon phthalocyanines (SiPcs) can also be applied as fullerene alternatives/acceptors in organic photovoltaic cells.  Our conclusion at the time was that phenoxylation enhances the performance of SiPcs as an electron transporting/accepting materials.  Over the past year we have enhanced this conclusion and formed an initial structure property relationship that gives a road map to synthetic alternatives of SiPcs that may ultimately yield higher performing OPVs. I will outline this structure property relationship and our future work in this area.

Coauthors will be cited as appropriate throughout the presentation.

References:

[1] (a) Cnops, K.; et al., Nature Comm., 5, Article number: 3406, doi:10.1038/ncomms4406. (b) Verreet, B.; et al., Adv. Energy Mater. 2014, 1301413, doi:10.1002/aenm.201301413.

[2] Ebenhoch, B.; et al., J. Mater. Chem. A, 2015, 3, 7345.

Our Relevant References:

“Boron subphthalocyanines as Singlet Fission Harvesting Materials within Organic Photovoltaics.” Castrucci, J.S.; Josey, D.; Thibau, E.; Lu, Z-H.; Bender, T.P.*; J. Phys. Chem. Lett., 2015, 6 (15), 3121–3125.

“Acceptor Properties of Boron Subphthalocyanines in Fullerene Free Photovoltaics.” Beaumont, N.; Castrucci, J.S.; Sullivan, P.; Morse, G.E.; Paton, A.S.; Lu, Z.H.; Bender, T.P.*; Jones, T.S.; J. Phys. Chem. C, 2014, 118(27) 14813–14823.

“The Position and Frequency of Fluorine Atoms Changes the Electron Donor/Acceptor Properties of Fluorophenoxy Silicon Phthalocyanines within Organic Photovoltaic Devices” Lessard, B.H.; Grant. T.; White, R.; Thibau, E.; Lu, Z-H.; Bender, T.P.*; J. Mater. Chem. C., 2015, accepted and under revision.

“Assessing the Potential Roles of Silicon and Germanium Phthalocyanines in Planar Heterojunction Organic Photovoltaic Devices and How Pentafluoro Phenoxylation Can Enhance π–π Interactions and Device Performance” Lessard, B.; Plint, T.; Castrucci, J.; White, R.; Josey, D.; Lu, Z.H.; Bender, T.P.*; ACS Appl. Mater. Inter., 2015, 7(9), 5076-5088.

“The Position and Frequency of Fluorine Atoms Changes the Electron Donor/Acceptor Properties of Fluorophenoxy Silicon Phthalocyanines within Organic Photovoltaic Devices” Lessard, B.H.; Grant. T.; White, R.; Thibau, E.; Lu, Z-H.; Bender, T.P.*; J. Mater. Chem. C., 2015, accepted and under revision.

“Assessing the Potential Roles of Silicon and Germanium Phthalocyanines in Planar Heterojunction Organic Photovoltaic Devices and How Pentafluoro Phenoxylation Can Enhance π–π Interactions and Device Performance” Lessard, B.; Plint, T.; Castrucci, J.; White, R.; Josey, D.; Lu, Z.H.; Bender, T.P.*; ACS Appl. Mater. Inter., 2015, 7(9), 5076-5088.