Ability To Fine-Tune the Electronic Properties and Open-Circuit Voltage of Phenoxy-Boron Subphthalocyanines through Meta-Fluorination of the Axial Substituent

Abstract

Six different boron subphthalocyanines with fluorophenoxy axial substituents were synthesized to explore and fine-tune the HOMO and LUMO energy levels based on past observations of the unique levels of pentafluorophenoxy-boron subphthalocyanine (F5BsubPc). Electrochemistry reduction potentials, ionization energies from ultraviolet photoelectron spectroscopy (UPS) measurements, and energy levels calculated using semiempirical methods reveal finely variable values between phenoxy-BsubPc (PhO-BsubPc), without any fluorine atoms, and F5BsubPc, with all five fluorines. There is no trend between the number of fluorines on the phenoxy group and the electronic properties, but there is an influence of meta fluorine(s) altering the redox potentials and ionization energy, leading us to categorize the fluorophenoxy-BsubPcs into two “buckets”: with and without meta fluorines. We then applied the fluorophenoxy-BsubPcs as electron acceptors in planar heterojunction organic photovoltaic devices. The categorization of these “buckets” was confirmed by the fine change in open-circuit voltage between 1.15 and 1.21 V, which is an exceptionally high value. This level of fine-tuning of properties and device metrics is a unique handle enabled by the phenoxy axial substituent of BsubPcs.

Phenoxy-(Chloro)n-Boron Subnaphthalocyanines: Alloyed Mixture, Electron-Accepting Functionality, and Enhanced Solubility for Bulk Heterojunction Organic Photovoltaics

“…This effect is also true for some phenoxylated BsubPcs. 27,39 The reversibility in both the oxidation and reduction region for the phenoxy Cl n BsubNcs is not overly surprising as the aromatic nature of the axial substituent combined with the more π-extended benzoisoindoline subunits are anticipated to stabilize the BsubNc in its radical anion or radical cation form. Differential pulse voltammetry (DPV, degassed DMF, 0.1 M TBAPC) was also carried out and it verified the CV results (Figure S8 and Table S9).…”

Exploring the Synthesis and Electronic Properties of Axially Substituted Boron Subphthalocyanines with Carbon‐Based Functional Groups

“…The subscript R is the reference fluorophore, F 5 PhO-BsubPc, with a reported Φ = 0.42 [9] in toluene at room temperature. This is a standard operating procedure from literature [32] and well established in our laboratory [9,33] for a series of BsubPcs; however, it has been revised for this study to extend the measurements for a wide range of BsubPcs with various maximum absorbance shifts in energy. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were carried out using a Bioanalytical Systems C3 electrochemical workstation (unless otherwise stated, specifically for CV traces stacked in Figure S6 and the data collated in Table S1).…”

Boron Subphthalocyanines and Silicon Phthalocyanines for Use as Active Materials in Organic Photovoltaics

“…Results demonstrated that α‐6T is suitable as a standard electron donor to pair with BsubPc derivatives in vacuum deposited PHJ devices, with even α‐6T/Cl‐Cl 6 BsubPc outperforming α‐6T/C 60 despite significant V OC losses. Several novel BsubPc derivatives were synthesized and paired with an α‐6T in subsequent studies . The ability to fine‐tune the V OC through peripheral chlorination was also demonstrated, although pairing α‐6T with BsubPcs with deep LUMO energy levels (Cl‐Cl 6 BsubPc, Cl‐Cl 12 BsubPc) substantially reduces the V OC and overall OPV performance.…”

“…An array of fluorophenoxy‐BsubPc (F n PhO‐BsubPc) compounds (Figure b ) ) were synthesized to investigate tunability of the HOMO/LUMO energy levels and electronic properties . The meta position was discovered to be the sole influencer on HOMO/LUMO, effectively dividing the array of F n PhO‐BsubPcs into two “buckets”.…”