Photoconductor-liquid crystal device

Similar photo-induced transient spectra are observed in dilute solutions of the oU-gomers, indicating that the fast optical transition is intramolecular. OASLMs based on oligo(thiophenes) are therefore not limited either by slow collective effects, as for hquid crystals or polarisation effects in photorefractive materials and multiple quantum wells, nor by RC time constants, as for hybrid photoconductor/liquid-crystal devices. 

It has recently been shown that organic photoconductor-liquid crystal sandwich cells can in theory act as dynamic scattering devices 164> and the technical possibilities ought to be tested. In this context, it should be noted that dyes can be used in two-layer photocondensers (consisting e.g. of phthalocyanine and a ferroelectric ceramic), which are very sensitive to light and have a response time of lO-4 to 10-3 Sec 165). 

Besides polyimides, photoconductive polymers with conjugated bonds also can be successfully used in liquid crystal spatial light modulators [262-264], The high resolution, mechanical and electrical stability and possibility for sensitization of the photosensitivity make the use of organic polymer photoconductors in spatial light modulators very attractive. Devices such as phase... 

Previous SLMs have used photoconductors coupled to liquid crystals [237, 238], multiple-quantum-well semiconductors [239] and silver haUde films [240] to exploit such effects as photorefraction [241], photochromism [242, 243] and saturable absorption, etc. The non-linear optical properties of oUgothiophenes make them promising candidates for active photochromic materials in optically-addressed spatial light modulator devices. In particular, speed and spatial resolution can be improved by two orders of magnitude, compared [244] with devices based on liquid crystals or semiconductor heterostructures. 

OPVs are suitable for various applications in materials science Organic light emitting diodes (OLED), field-effect transistors (FET), semiconductors (doped), photoconductors, solar cells, photovoltaic devices, optical brighteners, laser dyes, nonlinear optics (NLO), optical switching, imaging techniques, photoresists and liquid crystals [la-e, Ij-o, Ir, Iv, 27, 120]. Among these applications, two fields will be selected here, namely NLO and electroluminescence studies. 

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