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The effect of silver nanoplate (AgPL) on the singlet exciton fission (SF) of rubrene (Rub) was verified by examining the magnetic field effects (MFEs) on the SF of Rub through measuring magnetic field dependence of fluorescence intensity of Rub in two thick Rub polymer-composite films in the absence and the presence of AgPL. The fluorescence intensity of Rub in the Rub-AgPL polymer-composite film was larger than that in the Rub polymer-composite film. The enhancement (1.4 times) must be caused by strong electric fields due to localized surface plasmon resonance (LSPR) of the embedded AgPL near the Rub in polymer matrix. The magnitude of the MFEs in the Rub-AgPL polymer-composite film was almost same as those in the Rub polymer-composite film. These results strongly indicate that the efficiency of SF was enhanced by the LSPR due to the embedded AgPL into the polymer matrix in the Rub-AgPL polymer-composite film.

Effects of silver nanoplate (AgPL) and magnetic field on photon upconversion based on sensitized triplet-triplet annihilation (PUC-TTA) were examined in the system of platinum(II) octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA), when AgPLs were incorporated into polymer thin films containing PtOEP and DPA. In the presence of AgPL, the PUC emission intensity increased as compared with that in the absence of AgPL. The result is most likely attributable to the localized surface plasmon resonance of AgPL. On the other hand, in the absence of AgPL, the PUC emission intensity decreased in the presence of magnetic field, while in the presence of AgPL, the PUC emission intensity increased drastically in the presence of magnetic field. The synergetic effect of AgPL and magnetic field on the PUC emission intensity in PUC-TTA was observed for the first time. © 2019 The Japan Society of Applied Physics.

Well-ordered nanohole arrays on atomically flat gold (111) surfaces were fabricated by wet etching through block copolymer (BC) masks using ferri/ferrocyanide etchant. Amphiphilic BCs consisting of poly(ethylene oxide) (PEO) and liquid crystalline poly(methacrylate) with azobenzene mesogens [PMA(Az)], PEOm-b-PMA(Az)n, blended with poly(ethylene glycol) monomethylether (EO) form hexagonally arranged ion-transporting nanocylinders of EO-blended PEO microdomains in the BC masks. Atomic force microscopy (AFM) revealed a hexagonally arranged nanohole array on each terrace of the gold surface after the total wet nanopattering including a 5 min etching. The diameter (d) and distance between neighboring nanoholes (D) were controlled by the degree of polymerization of the BC. Two kinds of nanohole arrays with (d, D) = (12 nm, 25 nm) and (20 nm, 41 nm) were obtained in good agreement with the d and D of the EO-blended PEO microdomains of the masks. Scanning tunneling microscopy (STM) indicated that the depth of nanoholes was 3.5 A, corresponding to the thickness of a single atomic layer of gold, and the flatness of the bottom of the holes was confirmed.

A photoconductive atomic force microscope (AFM), which is a contact mode current-sensing AFM combined with an optical pumping laser, was developed in order to investigate the interaction between light and matter in a nanometer-scale tinny structure. The principle of the photoconductive AFM is the measurement of the photocurrent in an individual nanometer-scale structure, and also two-dimensional mapping of the photoelectric property by scanning the conductive cantilever on the surface of a sample. The photoelectric property of an organic thin film with copper phthalocyanine was demonstrated to test the performance of this system. Nanometer-scale point contact photocurrent, point contact current–voltage characteristics and photoconductive imaging could be attained using the system. Photoconductive AFM has the potential to be of use in various fields of nanometer-scale photonics.

Upon Nd-YAG laser irradiation of a Langmuir-Blodgett film containing Ru(II)-bipyridine metal complex, strong second-harmonic light at 532 nm is observed. The second-harmonic light intensity is remarkably suppressed when the ruthenium complex is excited by other laser pulses (either 355 nm or 460 nm) just before Nd-YAG laser irradiation at 1064 nm. This phenomenon is ascribed to the reduction in hyperpolarizability on going from the ground state to a metal-to-ligand charge-transferred excited state. The optical modulation of SHG becomes possible, for the first time, by the aid of laser-induced electronic transition.