A. H. J. Venhuizen

Photo- and electroluminescence efficiency in poly(dialkoxy-p-phenylenevinylene)

Abstract This paper presents the dependence of luminescence efficiency on the degree of conjugation for a soluble poly(dialkoxy- p -phenylenevinylene), comparing the photoluminescence yields with the electroluminescence yields. Photoluminescence efficiency increases with the fraction of non-conjugated units for polymers both in the solid state and in solution. The highest external electroluminescence efficiency measured is 1.4% (photons/electron) for a polymer having approximately 10% non-conjugated units. Electroluminescence efficiency depends not only on the radiative recombination efficiency of the emitting material but also on carrier transport into and within the material.

Electroluminescence and photoluminescence efficiency of poly(p-phenylenevinylene) derivatives

Abstract Alkoxy, alkyl, and cyano derivatives of poly( p -phenylenevinylene) [PPV] are used as the emissive layers in light-emitting diodes [LEDs] to obtain luminescence from red to blue. We present the luminescence efficiency for these soluble PPV derivatives. comparing the photoluminescence [PL] yields with the electroluminescence [EL] yields. PL efficiency increases with the fraction of non-conjugated units. EL efficiency depends not only on the radiative recombination efficiency of the emitting material but also on carrier transport to and within the material. Efforts to improve the efficiency and long term stability of these polymer LEDs are challenged by efficient and balanced carrier injection.

Behavior of a rectifying junction at the interface between porous silicon and its substrate

The current injection into metal/porous Si/bulk Si diodes is investigated by transport and photoresponse measurements. Under low forward bias, the diode current is determined by the space charge region at the porous Si/bulk Si interface. The activation energy of the photovoltage shows that holes are injected into porous Si states which have little quantum confinement. This is discussed in terms of the confinement model for porous Si photoluminescence.

Efficient modal dispersion phase‐matched frequency doubling in poled polymer waveguides

We report the design, manufacture, and characterization of poled polymer multilayer waveguides for frequency doubling. Phase matching is obtained by using modal dispersion between the zeroth‐order fundamental lightwave and the first‐order second‐harmonic wave. By incorporating a very thin high refractive index satellite layer, the phase‐match condition can be fulfilled with concomitant large overlap between the two waves, resulting in efficient doubling.

Linear optical properties of frequency doubling polymers

Measurements of linear optical properties of methylmethacrylate copolymers with non-linear optical 4-alkoxy-4′-alkylsulfone stilbene side-chains are presented. From there two methods for phase matching are discussed; one aiming to equalize the refractive indices of the fundamental and the second harmnic wave, the other to suppress the destructive character of the interference. The matter of photo stability of frequency doubling polymers is also discussed.