Synthesis, Characterization, and Transistor Response of Semiconducting Silole Polymers with Substantial Hole Mobility and Air Stability. Experiment and Theory

Abstract

Realizing p-channel semiconducting polymers with good hole mobility, solution processibility, and air stability is an important step forward in the chemical manipulation of charge transport in polymeric solids and in the development of low-cost printed electronics. We report here the synthesis and full characterization of the dithienosilole- and dibenzosilole-based homopolymers, poly(4,4-di-n-hexyldithienosilole) (TS6) and poly(9,9-di-n-octyldibenzosilole) (BS8), and their mono- and bithiophene copolymers, poly(4,4-di-n-hexyldithienosilole-alt-(bi)thiophene) (TS6T1, TS6T2) and poly(9,9-di-n-octyldibenzosilole-alt-(bi)thiophene) (BS8T1, BS8T2), and examine in detail the consequences of introducing dithienosilole and dibenzosilole cores into a thiophene polymer backbone. We demonstrate air-stable thin-film transistors (TFTs) fabricated under ambient conditions having hole mobilities as large as 0.08 cm(2)/V x s, low turn-on voltages, and current on/off ratios > 10(6). Additionally, unencapsulated TFTs fabricated under ambient conditions are air-stable, an important advance over regioregular poly(3-hexylthiophene) (P3HT)-based devices. Density functional theory calculations provide detailed insight into the polymer physicochemical and charge transport characteristics. A direct correlation between the hole injection barrier and both TFT turn-on voltage and TFT polymer hole mobility is identified and discussed, in combination with thin-film morphological characteristics, to explain the observed OTFT performance trends.

Improvement of short circuit current density by intermolecular interaction between polymer backbones for polymer solar cells

“…Compared with PBDTAQ, PBDTAFQ had 1.5 times the J SC because the conjugation length and the planarity of the fused-phenyl ring increased when compared with that of the separated phenyl ring. This is consistent with Marks and Xie co-workers 42 results indicating an increase in intermolecular charge transfer because of the effective π-π stacking of PBDTAFQ with its relatively high planarity. 44 The addition of 3 vol% DIO increased the efficiency of the PBDTAFQ:PC 70 BM blend-based devices (at a 1:5 ratio) to 3.2%.…”

“…PBDTAQ exhibited a relatively stronger (1 0 0) peak, and PBDTAFQ had a stronger (0 1 0) peak, which indicates that PBDTAFQ is face-on dominant while PBDTAQ is edge-on dominant. 42 The polymers' (1 0 0) diffraction peak (2θ) was at 5.17°a nd 4.33°, respectively. Based on Bragg's law (λ = 2d sin θ), the lamellar d-spacing (d l ) was calculated at 17.08 and 20.04 Å for each, and the (0 1 0) diffraction peak related to π-π stacking was at 20.36°a nd 22.68°for PBDTAQ and PBDTAFQ, respectively.…”

“…However, a peak in the high angle close to 15-25°was only seen in PBDTAQ, which means that PBDTAFQ has a strong tendency of having a face-on structure and PBDTAQ dominantly has an edge-on crystal structure. 43 Bo et al reported that two polymers with the same Pz acceptor had different types of crystal structure depending on the BDT donor's side chain. While P1 polymers had the same main monomer as the PBDTAFQ polymers in this study, a low (010) diffraction peak and a dominant edge-on orientation was observed owing to the impact of the spacer's alkyl side chain that was introduced to enhance solubility and also increased the tilt angle (θ 1 ).…”

Optical absorption and emission properties of end-capped oligothienoacenes: A joint theoretical and experimental study

“…In principle, a similar stabilizing effect is also expected for the case of the highest occupied molecular orbital (HOMO) in -conjugated systems. [40,41] However, as recently observed by Lu et al, [40] …”

Synthesis and optical and photovoltaic properties of dithienosilole–dithienylpyridine and dithienosilole–pyridine alternate polymers and polymer–B(C6F5)3 complexes

“…The absorption maxima were blue-shifted from those reported for DTS homopolymers (pDTS, l max ¼ 533-561 nm), 22,23 DTS-bithiophene alternate polymers (pDTS2T, 544-558 nm) 22,23 and a DTS-pyridinothiadiazole alternate polymer (pDTSPTA, 732 nm) 20 (Scheme 4). The introduction of pyridine units into pDTS2T and pDTS appeared to hinder the planarity of the resulting p-conjugated systems due to steric repulsion between the C-H bonds of the adjacent thiophene and pyridine rings.…”