The electrical and photoresponse properties of an Al/p-Si/organic layer/Al diode were investigated. The organic layer containing novel 2,2-bis[spiro(7,8-dioxy-4-methylcoumarin)]-4,4,6,6-bis[spiro(2',2"-dioxy-1',1"biphenylyl)]cyclotriphosphazene compound was coated by the drop casting method on p-Si having ohmic contact. The structural characterization of the novel cyclotriphosphazene compound was confirmed by using 1 H, 13 C and 31 P-NMR, elemental analysis and FTIR spectroscopic techniques. The diode exhibits a photoconducting and photodiode behavior under solar light illumination. The electrical parameters such as ideality factor, barrier height and series resistance of the diode were determined from I-V characteristics. It is seen that the photocurrent of the diode under illumination is higher than the dark current. Also, the frequency dependence of capacitance (C) and conductance (G) was explained on the basis of interface states. It is evaluated that the hybrid photodiode can be used as a photosensor in organic photodetector applications.

Co-sensitized solar cell was fabricated using CdS quantum dots with Lil based liquid electrolyte. The CdS quantum dots were deposited on TiO2 films by successive ionic layer adsorption and reaction (SILAR) method. The optical band gap values of the TiO2 and CdS films were determined to be 3.42 eV and 2.49 eV, respectively. The short-circuit photocurrent density (J(SC)) and the open-circuit voltage for the solar cell under AM 1.5 illumination were found to be 5.27 +/-0.02 mA/cm(2) and 0.5 +/-0.04 V, respectively. The efficiency of the solar cell was determined to be 1.33%. The efficiency of the solar cell is higher than that of efficiency of the co-sensitized solar cell fabricated using Ag2S/CdS quantum dots (1.27%) coupled with LiBOB-based liquid electrolyte. On the other hand, the efficiency of the solar cell is lower than that of dye-sensitized solar cell based on co-sensitization of TiO2 electrodes with CdS quantum dots and dye N719. These results indicate that the co-sensitization of TiO2 film can be provided with non-sulfur electrolyte and inorganic semiconductor QDs rather than organic dyes.

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