Electron-deficient π-conjugated small molecules can function as electron-transporting semiconductors in various optoelectronic applications. Despite their unique structural, optical, and electronic properties, the development of BODIPY-based organic semiconductors has lagged behind that of other π-deficient units. Here, we report the design and synthesis of two novel solution-proccessable BODIPY-based small molecules (BDY-3T-BDY and BDY-4T-BDY) for organic thin-film transistors (OTFTs). The new semiconductors were fully characterized by (1)H/(13)C NMR, mass spectrometry, cyclic voltammetry, UV-vis spectroscopy, photoluminescence, differential scanning calorimetry, and thermogravimetric analysis. The single-crystal X-ray diffraction (XRD) characterization of a key intermediate reveals crucial structural properties. Solution-sheared top-contact/bottom-gate OTFTs exhibited electron mobilities up to 0.01 cm(2)/V·s and current on/off ratios of >10(8). Film microstructural and morphological characterizations indicate the formation of relatively long (∼0.1 mm) and micrometer-sized (1-2 μm) crystalline fibers for BDY-4T-BDY-based films along the shearing direction. Fiber-alignment-induced charge-transport anisotropy (μ∥/μ⊥ ≈ 10) was observed, and higher mobilities were achieved when the microfibers were aligned along the conduction channel, which allows for efficient long-range charge-transport between source and drain electrodes. These OTFT performances are the highest reported to date for a BODIPY-based molecular semiconductor, and demonstrate that BODIPY is a promising building block for enabling solution-processed, electron-transporting semiconductor films.

The effect of 5 MeV high-energy proton irradiation on solution-processed metal-oxide thin-film transistors (TFTs) is investigated. The electrical characteristics of the devices are measured before and after proton irradiation with radiation doses of 10 13 , 10 14 , and 10 15 cm −2 . TFTs based on zinc oxide (ZnO) and amorphous indium gallium zinc oxide (a-IGZO) exhibit a significant negative shift in their threshold voltage values (ΔV th ≤ −30 V) or transitioned to the conductor state as the proton radiation dose increased. For a-ZnO and IGZO, this change in the electrical characteristics originates from the formation of proton-irradiation-induced oxygen vacancies in the metaloxide semiconductor layer. On the other hand, amorphous zinc tin oxide devices with an optimized composition exhibit relatively stable electrical characteristics when subjected to proton irradiation. Furthermore, the backchannel passivation of oxide-semiconductor TFTs with an n-type organic semiconductor layer significantly improves the device stability under proton irradiation. This study demonstrates that solution-processed metal-oxide semiconductors have significant potential as rad-hard large area electronic devices for nuclear and aerospace applications.

New ultralow bandgap semiconductor small molecules were designed and synthesized for ambient-stable and solution-processable ambipolar organic field-effect transistors and high-gain inverters.

The stabilization and control of the electrical properties in solution-processed amorphous-oxide semiconductors (AOSs) is crucial for the realization of cost-effective, high-performance, large-area electronics. In particular, impurity diffusion, electrical instability, and the lack of a general substitutional doping strategy for the active layer hinder the industrial implementation of copper electrodes and the fine tuning of the electrical parameters of AOS-based thin-film transistors (TFTs). In this study, the authors employ a multifunctional organic-semiconductor (OSC) interlayer as a solution-processed thin-film passivation layer and a charge-transfer dopant. As an electrically active impurity blocking layer, the OSC interlayer enhances the electrical stability of AOS TFTs by suppressing the adsorption of environmental gas species and copper-ion diffusion. Moreover, charge transfer between the organic interlayer and the AOS allows the fine tuning of the electrical properties and the passivation of the electrical defects in the AOS TFTs. The development of a multifunctional solution-processed organic interlayer enables the production of low-cost, high-performance oxide semiconductor-based circuits.

A series of novel solution-processable α,ω-disubstituted indeno[1,2-b]fluorene-6,12-dione-thiophene ambipolar semiconductors were developed and characterized in OTFT devices with favorable charge-transport properties.