p‐Type Doping of Poly(3‐hexylthiophene) with the Strong Lewis Acid Tris(pentafluorophenyl)borane

Abstract

State-of-the-art p-type doping of organic semiconductors is usually achieved by employing strong π-electron acceptors, a prominent example being tetrafl uorotetracyanoquinodimethane (F 4 TCNQ). Here, doping of the semiconducting model polymer poly(3-hexylthiophene), P3HT, using the strong Lewis acid tris(pentafl uorophenyl)borane (BCF) as a dopant, is investigated by admittance, conductivity, and electron paramagnetic resonance measurements. The electrical characteristics of BCF-and F 4 TCNQ-doped P3HT layers are shown to be very similar in terms of the mobile hole density and the doping effi ciency. Roughly 18% of the employed dopants create mobile holes in either F 4 TCNQ-or BCF-doped P3HT, while the majority of doping-induced holes remain strongly Coulomb-bound to the dopant anions. Despite similar hole densities, conductivity and hole mobility are higher in BCF-doped P3HT layers than in F 4 TCNQ-doped samples. This and the good solubility in many organic solvents render BCF very useful for p-type doping of organic semiconductors.

Self‐Healable and Stretchable Organic Thermoelectric Materials: Electrically Percolated Polymer Nanowires Embedded in Thermoplastic Elastomer Matrix

“…It should be noted that the neat BCF peak was not overlapped with any of the peaks in Figure b (Figure S2, Supporting Information). Given that two polaron peaks and a bipolaron peak of poly(3‐hexylthiophene) were positioned at 775.6, 867.8, and 761.35 nm, respectively, the broad absorption band from ≈750 to ≈1000 nm might have resulted from the formation of polarons and bipolarons in P3BT. However, it was difficult to clearly deconvolute the absorption band because the polaron and bipolaron peaks overlapped with the spectral features owing to the formation of a Lewis acid–base complex, water‐reactive adduct ((C 6 F 5 ) 3 B(OH 2 )), and other BCF‐related products .…”

“…Given that two polaron peaks and a bipolaron peak of poly(3‐hexylthiophene) were positioned at 775.6, 867.8, and 761.35 nm, respectively, the broad absorption band from ≈750 to ≈1000 nm might have resulted from the formation of polarons and bipolarons in P3BT. However, it was difficult to clearly deconvolute the absorption band because the polaron and bipolaron peaks overlapped with the spectral features owing to the formation of a Lewis acid–base complex, water‐reactive adduct ((C 6 F 5 ) 3 B(OH 2 )), and other BCF‐related products . The higher absorption intensity at around 615 nm in the spectrum of the SIS/P3BT/BCF composite solution compared to the absorption intensity in the spectrum of the as‐dissolved SIS/P3BT composite solution suggests the presence of BCF anions and P3BT nanowires in the former .…”

“…However, it was difficult to clearly deconvolute the absorption band because the polaron and bipolaron peaks overlapped with the spectral features owing to the formation of a Lewis acid–base complex, water‐reactive adduct ((C 6 F 5 ) 3 B(OH 2 )), and other BCF‐related products . The higher absorption intensity at around 615 nm in the spectrum of the SIS/P3BT/BCF composite solution compared to the absorption intensity in the spectrum of the as‐dissolved SIS/P3BT composite solution suggests the presence of BCF anions and P3BT nanowires in the former . This result therefore implies that P3BT self‐assembled to form nanowire networks in the SIS matrix and that BCF effectively doped the P3BT nanowires in the composites.…”

“…Although the peak intensities decreased with increasing doping concentration, the p‐doped P3BT still showed good molecular ordering, except in the case of addition of excessive BCF (ϕ BCF = 40.5 mol%). The addition of BCF dopant molecules could hinder efficient crystal packing of P3BT, mainly because the bulky dopant molecules strongly interacted with the polymer backbones . In detail, the interaction between the P3BT nanowires and bulky pentafluorophenyl moieties in BCF molecules could possibly cause the reduction in polymer crystallinity.…”

“…Poly(3‐butylthiophene‐2,5‐diyl) (P3BT) was used as a polymer semiconductor, and it was engineered to form nanowires in the SIS matrix for the creation of electrically percolated charge transport pathways . In addition, the P3BT nanowires were p‐doped with a Lewis‐acid‐type molecular dopant, tris(pentafluorophenyl)borane (BCF), in order to enhance the electrical properties of the composites . The resulting SIS/P3BT/BCF composites exhibited meaningful TE performance at optimal concentrations of P3BT and BCF.…”