Investigation of crystal violet dye sensitized p-CuSCN / n-Cu20 junction photoelectrode in solar energy conversion devices

Abstract

A stable solid state photovoltaic cell is presented by sandwiching crystal violet dye between n-Cii20 prepared on a copper substrate and p-CuSCN transparent thin film prepared on n- CU2O considerably improving a previously presented (82) solid state photovoltaic cell made from bare p-CuSCN. After sandwiching crystal violet dye between n-Cu20 and p-CuSCN a photocurrent enhancement can be observed clearly compared to the solid state photovoltaic cells made with bare n-Cu20, n-Cu20/p-CuSCN and dye deposited p-CuSCN. This photocurrent enhancement with connection to the dye sensitized junction photoelectrode is due to the efficient charge separation process provided at the space charge layer. The variation of photocurrent quantum efficiency (<J)%) obtained due to dye sensitization with dye concentration (D0) of the device is presented. A relationship (|) = AD0-BD0 is found by solving the rate equations related to the dye sensitization. Parameters A and B are obtained relating to the rate constants and various factors which can be influenced to cj). Demonstrating various experimental results, kinetics of the photocurrent generation in the solid state photovoltaic cell is discussed. A photoelectrochemical cell is made by sandwiching a dye between p-CuSCN and n-Cu20 semiconductor films. A photocurrent enhancement is clearly found for the dye sensitized junction photoelectrode n-Cu20/Dye/p-CuSCN in comparison to that of the systems p- CuSCN/Dye, n-Cu20/p-CuSCN or n-Cu20 bare photoelectrochemical cells. Well cleaned copper substrates are boiled 15min in a 10'4M CUSO4 solution to fabricate n-Cu20 films to prepare Cu/n-Cu20 photoelectrodes. Cu/n-Cu20 films are immersed in a p-CuSCN preparation solution to fabricate transparent p-CuSCN thin films, to prepare Cu/n-Cu20/p- CuSCN junction photoelectrode. Thereafter, Cu/n-Cu20/p-CuSCN films are immersed in a 10' M Crystal Violet Dye solution for several minutes to prepare Cu/n-Cu20/Dye/p-CuSCN photoelectrodes. XRD data reveal that the formation of n-Cu20 and p-CuSCN thin films in the Cu/n-Cu20/p-CuSCN junction photoelectrode. The reason for the photocurrent enhancement in the Cu/n-Cu20/Dye/p-CuSCN is the efficient charge separation provided at n-Cu20/p-CuSCN junction for the photogenerated carriers created by the dye sensitization process associated with p-CuSCN transparent thin film and the direct light absorption of the n-Cu20 film. A dye sensitization process between the dye and the n-Cu20 films is not observed. 10"4M Fe2+/Fe3+ redox couple is used as the electrolyte.