Monitoring of Crystallization Process in Solution-Processed Pentacene Thin Films by Chemical Conversion Reactions

Solution-processable organic semiconductors having bulky substituent groups on the π-conjugated skeleton are rapidly gaining attention for their potential applications to large-area electronics. While the substituent groups contribute to the good solubility in organic solvents, they give rise to hopping sites in a thin film, affecting adversely the charge-carrier transport. As an alternative material, a solvent-soluble precursor compound with thermally cleavable functional groups is promising, which can be converted by heat treatment into a thin film to generate the desired material consisting solely of conjugated systems. This precursor approach is practically applied to various thin-film-based devices. The overall process of the thin film growth, however, remains unrevealed. In the present study, solution-processed pentacene thin films are prepared from a thermally convertible precursor, and the structural evolution during the chemical conversion reaction has been revealed by a combination of cutting-edge analytical tools of two-dimensional X-ray diffraction (2D-GIXD) and p-polarized multiple-angle incidence resolution spectrometry (pMAIRS). The highlight is that pentacene is crystallized in a stepwise manner in the thermally converted films, which is substantially different from a typical growth process. In addition, influences of the oxidation reaction of pentacene on the molecular arrangement are also discussed quantitatively. This study provides a fundamental schematic of thin films grown by the precursor method

Controlling Major Portal Vein Invasion Progression during Lenvatinib Treatment by Carbon-Ion Radiotherapy in Patients with Advanced Hepatocellular Carcinoma

Macrovascular invasion (MVI), including portal vein tumor thrombosis (PVTT), is strongly associated with poor prognosis in patients with hepatocellular carcinoma (HCC). While recommended standard treatment for patients with advanced HCC is systemic therapy, various treatment approaches, including resection, transarterial chemoembolization, and radiation, have been empirically suggested to improve prognosis by eliminating or controlling MVI. Herein, we report our experience of a case with advanced HCC where MVI was controlled by carbon-ion radiotherapy (CIRT) while on systemic therapy, resulting in a prolonged survival. A female patient with HCC in her early 60s had multiple intrahepatic lesions (maximum 60 mm in diameter) with PVTT. The PVTT of this patient had reached the main trunk of the portal vein despite the use of lenvatinib. The other intrahepatic lesions of the patient, except PVTT, had been controlled by lenvatinib. Therefore, hoping to control PVTT, we attempted CIRT. The patient resumed lenvatinib therapy after the irradiation. During lenvatinib re-treatment, no evident progression of PVTT was observed in the patient