Boron Subphthalocyanines as Triplet Harvesting Materials within Organic Photovoltaics

Abstract

Singlet fission, the generation of two excited triplet states from a single absorbed photon, is currently an area of significant interest to photovoltaic researchers. In this Letter, we outline how a polychlorinated boron subphthalocyanine, previously hypothesized to be an effective harvester of singlet fission derived triplets from pentacene, is relatively efficient at facilitating the process. As expected, we found a major increase in photocurrent generation at the expense of device voltage. For a direct point of comparison, we also have paired the same polychlorinated boron subphthalocyanine with α-sexithiophene to probe the alternative technique of complementary absorption engineering. The sum of these efforts have let us present new guidelines for the molecular design of boron subphthalocyanine for organic photovoltaic applications.

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

“…As with tetracene, V OC tunability of pentacene/BsubPc OPVs was demonstrated through variation of the BsubPc peripheral chlorination, comparing Cl‐BsubPc, Cl‐Cl 6 BsubPc, and Cl‐Cl 12 BsubPc as electron acceptors (Figure ) . For the first time with BsubPcs, triplet harvesting became evident when pairing pentacene with Cl‐Cl 6 BsubPc and Cl‐Cl 12 BsubPc.…”

“…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.…”

Facile Synthesis, Triplet‐State Properties, and Electrochemistry of Hexaiodo‐Subphthalocyanine

“…The recent surge of interest in this class of compounds stems from their unique and tunable optical and electrochemical properties, such as strong absorption of light in the visible part of the spectrum, tunable HOMO/LUMO energy levels, and triplet‐state characteristics. Currently, subphthalocyanines are tested mainly as functional materials in applications such as photoactive components of solar cells, organic light‐emitting diodes (OLED), organic field‐effect transistors (OFETs), and non‐linear optic (NLO) materials …”

“…[26] The recents urge of interesti nt his class of com-pounds stemsf rom their unique and tunable opticala nd electrochemical properties, such as stronga bsorption of light in the visible part of the spectrum,t unable HOMO/LUMOe nergy levels, andt riplet-state characteristics.C urrently,s ubphthalocyaninesa re tested mainly as functionalm aterials in applications such as photoactive components of solar cells, organic light-emitting diodes (OLED), organic field-effect transistors (OFETs), and non-linear optic (NLO) materials. [24,[27][28][29][30][31] In this report, we wish to introduce the facile synthesis as well as the photochemical and electrochemical characterization of two examples of halogenated subphthalocyanines (I 6 SubPcs). The peripheral positions of the aromatic rings were substituted with six iodine atoms in order to induce highly desirable photophysical properties through inducing an efficient spin-orbit coupling and facilitatei ntersystem crossing.…”

Hexachlorinated Boron(III) Subphthalocyanine as Acceptor for Organic Photovoltaics: A Brief Overview

“…As seen from Table 1, the HOMO-LUMO values obtained by various methods/ research groups fluctuate within the range of ±0.2 eV. Moreover, different numbers can be reported in the articles by the same authors ( [20] vs. [28] or [21] vs. [22]). Such discrepancies are not surprising, considering the diversity of approaches/ methods used for estimation [36].…”