A mild and versatile solution process enables the controlled preparation of multicomponent organic small-molecule thin films.

A series of thiazole-fused benzothiadiazoles were designed and synthesized, and their structural, electrochemical, and photophysical properties were analyzed. The observed high solubility, in combination with desirably high levels of electron-accepting ability and planarity in the solid state, promises great potential for the application of these compounds as π-electron-accepting building blocks in organic electronic materials. In addition, the two-dimensional expansion of π conjugation through the fused thiazole moiety renders these compounds ideal candidates for use as T-shaped π-conjugation junctions.

Acenes and their derivatives are commonly employed in organic electronics studies. However, they often lack the required solubility for solution deposition, which considerably limits their applicability to cost-effective devices. One of the proposed methodologies to evade this obstacle is the precursor approach, in which a soluble precursor is first deposited by a solution process then converted to a target acene compound within resulting thin films. The focus of this study is to develop solution-processed thin-film organic photovoltaic (OPV) cells by employing α-diketone derivatives of acenes in active-layer deposition by the precursor approach.1 α-Diketone-type precursors are characterized by clean, quantitative conversion to corresponding acene compounds by visible-light irradiation even in the solid state. For example, anthradithiophene (ADT) can be obtained from its α-diketone-type precursor (ADTDK) in thin films, allowing solution-process fabrication of planar-junction OPV cells based on ADT as a p-type semiconductor. The maximum photo-conversion efficiency (PCE) of 1.54% was obtained when PC71BM was used as an n-type semiconductor.2 In another case, dithienylanthracene (DTAnt) was generated in thin films from its precursor DTAntDK, and the combination with PC71BM led to 1.66% PCE in a p–i–n type OPV cell. Results with more p-extended systems will also be presented. Suzuki, M.; Aotake, T; Yamaguchi Y.; Noguchi, N.; Nakano, H.; Nakayama, K.; Yamada, H. J. Photochem. Photobiol. C. 2014, 18, 50–70. Yamada, H.; Yamaguchi, Y.; Katoh, R.; Motoyama, Y.; Aotake, T.; Kuzuhara, D.; Suzuki, M.; Okujima, T.; Uno, H.; Aratani, N.; Nakayama, K. Chem. Commun. 2013, DOI: 10.1039/C3CC46178E.