Wet chemical synthesis of ZnO thin films and sensitization to light with N3 dye for solar cell application

Abstract

Simple wet chemical synthesis of ZnO thin films has been carried out at room temperature (27 °C) from an aqueous alkaline bath followed by annealing in air at 100 °C on fluorine doped tin oxide coated glass substrates. The deposited film showed an optical band gap of 3.28 eV with a thickness of about 40 µm with a hexagonal crystal structure. A flower-like surface morphology consisting of petals was observed. These petals are made up of a fibrous network with interconnected nanoparticles leading to a high surface area. This obliged us to use this structure for dye-sensitized solar cells with lower fabrication process cost than conventional high temperature sintered methods which are commonly used for ZnO and TiO2. It would be advantageous to use a flexible plastic substrate instead of routine glass in future. ZnO showed a current conversion efficiency (η) of 0.34% with chemically adsorbed N3 dye at standard AM 1.5 condition with illumination of light intensity 100 mW cm−2.

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

“…As noted above, we collected a large number of published Tauc analyses of undoped ZnO that included plots of the absorbance data against the photon energy . This was critical, as our assessment of the application of the Tauc method required the consistent application of a fitting method, as described below.…”

Nanobeads of zinc oxide with rhodamine B dye as a sensitizer for dye sensitized solar cell application

“…By using the same precursor's solution and by depositing the films for about 40 h, we have previously reported ZnO films consisting of flower-like surface morphology [33]. In present study, the deposition parameters and rate of reactions were controlled by complexing agent (ammonia) in the bath and the reaction was carried out for 20 h instead of 40 h. This leads to the formation of small size nanoparticles (3-5 nm) at the FTO interface and then turns to bigger size particles (nanobeads, 20-30 nm) due to agglomeration of smaller once and limits flower like morphology which was due to secondary growth as reported previously.…”

Growth of novel ZnO nanostructures by soft chemical routes

“…The rapid evaporation of water from the ZnO layer and the heat treatment in the hot air flux coming from the hot surface will maintain long-range order structure of the ZnO particles, forming highly crystalline structure [19]. The mean crystallite sizes of the ZnO films were determined using the (0 0 2) peak and the Debye-Scherrer's equation [20] given by:…”