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A study was conducted of new photovoltaic devices based on donor-acceptor molecular and conducting polymer systems. The findings indicate that selective doping can provide low serial resistance and form internal fields for the collection of charges. In undoped parts, there was effective photogeneration of excitons. Further studies are recommended to maximize the potential of these new photocells.

Vapor-deposited multilayer structure was used to fabricate multicolor-emitting organic electroluminescent diodes. Multicolor emission was made possible by two types of layer structure. In the Type I devices, opposite polarity of electric field was applied to alter emission colors. In the Type II devices, different strength and polarity of electric field was applied to alter emission colors.

The vacuum evaporation technique was used to fabricate electroluminescent (EL) diodes utilizing metal-free phthalocyanine. The analysis included the EL characteristics of the EL diodes depending upon metals of the cathode electrode and the diodes' characteristics. The results indicate that the infrared electroluminescence resulted from the radiative transition corresponding to the Q band of H2Pc.

Molecular orientation, molecular packing structure, and electrical properties of thermally stable phthalocyanine, tert‐butylated phthalocyanine (t‐BuPcH2) in the thin film fabricated by bar‐coating method were investigated. The XRD patterns indicated that the columns composed of t‐BuPcH2 molecules formed hexagonal structure, the axis of which was parallel to the bar‐sweep direction, and t‐BuPcH2 molecules were vertically aligned to the bar‐sweep direction. Uniaxially oriented thin films of t‐BuPcH2 were successfully fabricated on Si substrate covered with polyimide by bar‐coating method, and the field effect mobility of t‐BuPcH2 was estimated to be 1.32 × 10−4 cm2 V−1 s−1 at maximum. The field effect mobility parallel to the bar‐sweep direction was approximately three times higher than that perpendicular to the bar‐sweep direction due to high electrical conduction along the column axis of t‐BuPcH2. [ABSTRACT FROM AUTHOR]

We propose a device structure to lower the lasing threshold of a uniformly lying helix cholesteric liquid crystal (ChLC) laser. We place a π-conjugated polymer active layer beneath the ChLC layer to provide auxiliary gain, and demonstrate an improvement in the lasing threshold by a factor of 2.3. We also perform finite difference time domain calculations coupled with rate equations for a four-level system, and clarify the effect of the additional active layer on both the photonic density of states and the inversion population density. Although the addition of an extra layer lowers the photonic density of states, the gain provided by the auxiliary layer is sufficient to overcome the losses and decrease the lasing threshold. Our concept is useful for obtaining high-performance ChLC lasers. [ABSTRACT FROM AUTHOR]

The stereoregularity effect on carrier mobility of stereoregular poly(N-vinylcarbazole) (PVK) was studied using metal–insulator–semiconductor charge extraction by the linearly increasing voltage technique. The hole mobility of stereoregular PVK thin film was dependent upon the stereoregularity (mm) and was enhanced to be 4.02 × 10−6 cm2 V−1 s−1 at mm = 94%, which was 4.8 times higher than that at mm = 50%. Furthermore, the activation energy depending on the stereoregularity of PVK was evaluated to be from 118 meV (mm = 50%) to 111 meV (mm = 94%) in faint variation. The enhanced carrier transport in the stereoregular PVK thin film was discussed by taking the stereoregularity involved with the intramolecular interaction through the carbazole substituents into consideration. [ABSTRACT FROM AUTHOR]

Uniaxially orientated thin film of phthalocyanine with bulky tert-butyl substituents (t-BuPcH2) was fabricated by bar-coating method. The thin film exhibited high dichroic ratio of more than 50 in the polarized absorption. Molecular packing structure of t-BuPcH2 in the thin film was suggested by using the results of XRD measurements, in which the molecular plane of t-BuPcH2 was determined to be perpendicular to the substrate and bar-sweep direction. In addition, the X-ray rocking curve measurements demonstrated that t-BuPcH2 possessed highly molecular orientation in the thin film fabricated by bar-coating method. [ABSTRACT FROM AUTHOR]

Homogeneous alignment of a π-conjugated polymer, poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C16), was obtained by bar-coating method in thin film. The macroscopic direction of the main chain orientation, that tended to be parallel or perpendicular to the coating direction, strongly depended on the coating speed. The optical and electrical anisotropies of the bar-coated thin film were demonstrated. By observing the surface morphology, it is revealed that the coating speed affected the polymeric aggregation. The molecular orientation mechanism through the polymeric aggregation in the coating process was discussed. [ABSTRACT FROM AUTHOR]