Chromophoric conditioning of photoelectric response in polar molecules

The photo-induced electrical conductivity of a number of arylidene-1,3-indandiones was investigated in order to determine the effect of charge carrier generation on the intramolecular electron shifts. The variation in the polarity of the compounds was achieved by placing electron donor and electron acceptor substituents on the arylidene group. The comparison of dark and photoconductivity of 15 arylidene-1,3-indandiones was obtained on sandwich cells of polycrystalline layers. More detailed experiments with the better photoconductors were carried out with sublimed films and pressed pellets.The photoconductivity of benzylidene derivatives indicated that photoconductivity increases with polarity of the molecule and achieves a maximum value in p-dimethylaminophenyl compound (DMAPID). Photovoltaic cells, giving 1.17–1.24 V open circuit photovoltage, were prepared from DMAPID sublimed film sandwich cells. The spectral response, voltage dependence and temperature dependence of several photoconductors were investigated. Although the generation of light-induced charge carriers is facilitated by increasing the dipole moment, the dark conductivities remained unaffected by such structural modifications.