Solution Processable Pentafluorophenyl End‐Capped Dithienothiophene Organic Semiconductors for Hole‐Transporting Organic Field Effect Transistors

Abstract

Two solution‐processable organic semiconductors, DFPT‐DTTR (1) and DFPbT‐DTTR (2), composed of pentafluorophenyl (FP) end‐capped 3,5‐dialkyl dithienothiophene (DTTR) core with thiophene (T) or bithiophene (bT) as π‐bridged spacers are developed and investigated for their optical, electrochemical, microstructural, and electrical properties. With more conjugated bithiophene units, compound 2 exhibits a red‐shifted UV–vis absorption band and upshifted HOMO/downshifted LUMO energy levels. According to the density functional theory, compound 2 features a more twisted molecular structure due to the intrinsic non‐coplanar blocks in the π‐backbones. Compound 1‐based organic field effect transistors exhibit efficient hole transport with mobility up to 0.48 cm2 V−1 s−1. This is one of the high mobility organic semiconductors exhibiting p‐channel characteristics based on solution‐processable small molecular FP end‐capped fused/oligothiophenes. With large and interconnected crystalline morphologies, decreased π–π stacking distance, and less steric hindrance, compound 1 exhibits two orders of magnitude higher mobility than the more distorted 2, which exhibits lower hole mobility of 1.82 × 10−3 cm2 V−1 s−1.

Fused thiophene based materials for organic thin‐film transistors

“…To investigate the charge transport property of compound 26 in solution‐processable n‐type OTFTs, alkyl groups are introduced in the center DTT core and compound 35 is synthesized along with 36 , with π‐extended conjugation by inserting one more thiophene ring on both sides, for comparison. [ 39 ] The lower HOMO energy levels of 34 and 35 suggest that both are environmentally stable. Compound 35 fabricated by a solution‐shearing method demonstrates higher mobility of 0.48 cm 2 V −1 s −1 , with an on/off ratio of 10 4 , because of a less twisted molecular backbone and closer π‐π stacking arrangement.…”

Bicyclopentadithiophene-Based Organic Semiconductor for Stable and High-Performance Perovskite Solar Cells Exceeding 22%

“…The DPV data clearly confirms that the variation in the alkyl chain (branched octyl vs linear octyl) has no significant effect on the electrochemical properties of NFAs, and each pair possesses similar oxidation and reduction potentials. , In contrast, halogenated compounds 2 and 3 feature more positive oxidation ( E ox = +1.23 V) and reduction ( E red = −0.28 V) potentials in comparison to their analogue 1 ( E ox = +1.17 V, E red = −0.40 V), which leads to lower HOMO (−5.67 eV) and LUMO (−4.16 eV) vs seen with nonhalogenated 1 [HOMO (−5.61 eV) and LUMO (−4.04 eV)]. Due to the electron-deficient nature of the halogenated indanones, compounds 2 and 3 display a shift toward higher values in both oxidation and reduction potentials in comparison to the potentials noticed for 1 . ,, In particular, the LUMO levels of halogenated NFAs ( 2 and 3 ) are much lower than those of nonhalogenated ones ( 1 ), comparing the difference in HOMO levels, resulting in the energy gap contractions of NFAs 2 and 3 compared to 1 . Consequently, the narrower energy gaps were confirmed for the halogenated 2 – 3 (∼1.50 eV) vs 1 (1.56 eV), which is in line with their optical energy gap values: 2 – 3 (∼1.44 eV) < 1 (1.49 eV).…”

Acetylene bridged alkoxyphenanthrene and triarylamine-based triads for low threshold voltage with high mobility OFETs

“…The performances of the TAA endcapped PN-based devices are competent with recently reported results on air-stable, solution-processed FETs from organic small molecular systems. [60][61][62]…”