Acenes are highly promising p-type organic semiconductors, and have been the subject of intense studies. However, acenes are often low in solubility and stability, which poses major obstacles in the synthesis and processing of this class of compounds. In order to overcome the problem, a series of diketone-type acene precursors have been developed. These precursors are generally more soluble and stable than the corresponding acene compounds, and their quantitative conversion can be achieved simply by photoirradiation both in solution and in the solid state. Further, the irreversible photoinduced removal of the -diketone unit can be used to alter the optoelectronic properties of fluorophores. This review overviews the synthesis and photochemical properties of -diketone-type acene precursors, as well as their use as intermediates in preparation of large acenes or highly functionalized acene derivatives. Computational studies on the mechanism of -diketone photolysis and the use of diketone derivatives in fabrication of organic devices are also summarized in this review.

In this paper, we describe a three-layer-stacked color image sensor comprising two organic photoconductive films (OPFs) with thin-film transistor-based readout circuits and a complementary metal–oxide–semiconductor (CMOS) image sensor. In this three-layer-stacked sensor, a blue-sensitive OPF selectively absorbs blue light, a green-sensitive OPF selectively absorbs green light, and a CMOS image sensor (CIS) receives red light. Color video imaging operation at 60 frames per second was confirmed for a prototype sensor having 320 × 240 pixels with a pixel pitch of 20 μm without a color filter array, and good color separation and a linear response of the sensor were achieved owing to the combination of the CIS and color-selective OPFs.

Besides the typical n-p* absorption of C=O moiety around 468 nm and anthracene-like absorption at 333, 349, and 367 nm, a broad absorption was observed around 386 nm, which can be assigned to an intramolecular CT absorption from anthracene to C=O moiety. 5,14-a-Diketopentacene could be converted to pentacene quantitatively by photoirradiation at 405 nm and 468 nm in toluene with a quantum yield of 2.3 and 2.4%, respectively, and these values are higher than 1.4% of 6,13-a-diketopentacene irradiated at 468 nm. The quantum yields in acetonitrile were lowered to 0.28 and 0.33% with irradiation at 468 and 405 nm. The crystal structure of 5,14-a-diketopentacene showed CHp interaction and p-p stacking between neighboring anthracene moieties and benzene moieties. The lower solubility of 5,14-adiketopentacene compared to the 6,13-isomer could be explained by this crystal structure.

Hole mobility was evaluated by top-contact bottom gate field effect transistor and time resolved microwave conductivity measurements in 2,6-dithienylanthracene and hexyl-substituted 2,6-dithienylanthracene films prepared by spin-coating of their α-diketone precursors followed by photoirradiation, revealing enough high potentials for semiconducting films with charge carrier mobilities of 0.8-0.9 cm(2) V(-1) s(-1) in the photo-irradiated films.

Stable 9,9'-anthryl-anthroxyl radicals were synthesized and isolated, and the structures were fully characterized by single crystal X-ray diffraction analysis and ESR measurement. The resonance structure and steric protection of the peripheral positions and the most reactive 9-position of anthracene prolong the half-life of the radical in solution to 11 days.