High‐qality self‐assembled heterostructures for polymer LEDs have been fabricated from PPV and newly synthesized copolymers of PPV and naphthalene. It is shown that the layer‐by‐layer self‐assembly of multilayer structures has advantages with respect to control of the thickness and homogeneity of the polymer films compared to the conventional spin coating technique. The fabrication and characterization of the heterostructures are detailed and features of the electroluminescence and photoluminescence discussed.

We present photoluminescence (PL), UV absorption, electroluminescence and x-ray reflectivity studies of self-assembled multilayer films containing alternate layers of conjugated copolymers, and nonconjugated insulating polymers. We show that the PL emission properties of these organic quantum wells can be ‘‘tuned’’ by a proper choice of the conjugated copolymer and the thickness of the insulating layers. Particularly, some of the self-assembled ultrathin films containing thin (∼7 Å) insulating polymeric layers exhibit a blue shift upon decreasing the thickness of the assembly. The PL shift is roughly proportional to 1/d2 where d is the thickness of the assembly, as expected for confined photogenerated electron-hole pair in an infinite square potential well. In contrast, the PL emission of similar assemblies but containing thick (∼40 Å) insulating layers is independent of the assembly thickness and exhibit emission in the blue. This may suggest a strong spatial confinement. Light emitting diodes based on self-assembled multilayer films with improved efficiency and stability and with threshold voltage as low as 2.6 V could be fabricated.

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We have studied the effect of chopped laser irradiation (λL=514 nm) on the resonant frequency (f0≊5.4 GHz) of a superconducting parallel-plate resonator (PPR) consisting of two thin epitaxial YBa2Cu3O7−x films. We demonstrate that laser irradiation shifts the resonant frequency of the PPR with negligible change of quality factor. Photoinduced deviation of f0 strongly depends on the chopping frequency and increases linearly with light intensity. The effect of illumination is attributed to the photoinduced change of the kinetic inductance due to laser heating. This effect may be used to produce phase modulation of the superconducting transmission lines.