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For more than two decades, the silylethyne functionalization scheme has been used to induce strong π-stacking interactions in linear acenes and heteroacenes. As part of our efforts to better understand the crystal engineering aspects of silylethyne functionalization, along with an interest in studying the impact of ring topology on the electronic and optical properties of heteroacenes, we describe here the integration of thieno[3,2- b ]thiophene (a non-linear isomer of the well-known anthradithiophene) into our well established crystal engineering scheme. By utilizing the thienothiophene moiety coupled with an asymmetric solubilizing group (isopropenyldiisopropylsilylethyne), we were able to achieve charge carrier mobilities ( μ ) upwards of 0.22 cm 2 V −1 s −1 . Based on their increased stability and promising initial mobilities, the use of this thienothiophene moiety may offer a new approach to the formation of larger heteroacene analogues with more than 5 aromatic rings. 

Fluoroanthradithiophenes are well known organic semiconductors, where alkynyl substituents featuring silicon and germanium exhibit hole mobilities in excess of 5 cm 2 V −1 s −1 . A key feature to achieve these performance levels is the 2-dimensional brickwork packing of triethylsilyl and triethylgermyl side chains, which direct solid-state packing, increase molecular stability, and increase solution processability for cheap and large scale fabrication. We have recently reported side chains utilising carbon in place of the other group 14 atoms, resulting in less favourable 1-dimensional molecular packing. Here we present the synthesis of new derivatives which adopt 2-D brickwork packing without the use of silicon or germanium to determine substituent effects on charge carrier mobility. 

The dynamics of triplet and singlet exciton populations in organic semiconductors offer interesting possibilities in improving optical device efficiency, while also attracting interest for future applications as manipulable states for quantum-state based computing. For technological applications, transduction of the exciton state is essential, thus detailed information on how the exciton dynamics affect device outputs is required. In this study, we measure the magnetic field response of the photocurrent in organic transistors to investigate the electrical signal resulting from singlet–triplet exciton dynamics. We find that controlling the orientation of the magnetic dipole orientation of the triplet by varying both the magnitude and orientation of the magnetic field with respect to single crystal axes in anti -2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene ( a diF TES ADT) allows us to manipulate the amount of current detected as a result of singlet fission. 

A carbon side-chain analogue to the high-performance organic semiconductor triethylsilylethynyl difluoroanthradithiophene has been synthesised and characterized. Atomic substitution of carbon for silicon results in subtle changes to opto-electronic properties, which are rationalised by density functional theory and balance of electron donating and withdrawing effects. Larger differences are observed in photostability and solid-state packing of the new material in comparison to known silicon and germanium derivatives. Comparison of the group 14 elements teaches us about the newly synthesised system, but also how the silylethynyl substituents used for the last two decades contribute to successful employment of functionalised polycyclic aromatic hydrocarbons as organic semiconductors. 

Photoinduced electron transfer into mesoporous oxide substrates is well-known to occur efficiently for both singlet and triplet excited states in conventional metal-to-ligand charge transfer (MLCT) dyes. However, in all-organic dyes that have the potential for producing two triplet states from one absorbed photon, called singlet fission dyes, the dynamics of electron injection from singlet vs. triplet excited states has not been elucidated. Using applied bias transient absorption spectroscopy with an anthradithiophene-based chromophore ( ADT-COOH ) adsorbed to mesoporous indium tin oxide ( nanoITO ), we modulate the driving force and observe changes in electron injection dynamics. ADT-COOH is known to undergo fast triplet pair formation in solid-state films. We find that the electronic coupling at the interface is roughly one order of magnitude weaker for triplet vs. singlet electron injection, which is potentially related to the highly localized nature of triplets without significant charge-transfer character. Through the use of applied bias on nanoITO : ADT-COOH films, we map the electron injection rate constant dependence on driving force, finding negligible injection from triplets at zero bias due to competing recombination channels. However, at driving forces greater than −0.6 eV, electron injection from the triplet accelerates and clearly produces a trend with increased applied bias that matches predictions from Marcus theory with a metallic acceptor. 

Dehydroannulenes are alkyne‐rich macrocycles possessing rigid, planar, π‐conjugated backbones. Octadehydro[12]annulenes in particular are formally antiaromatic, and have been shown to possess stable reduced states with exploitable LUMO energies. However, very few examples of this type of annulene have been structurally characterized, and there is little information on the stability of these antiaromatic molecules in solution or in the solid state. We have synthesized a range of substituted octadehydro[12]annulenes, and characterized their optical and redox properties. Contrary to prior reports, dehydro[12]annulenes with overlapping π‐surfaces are reasonably stable both in solution and thin films, suggesting potential use in practical applications.