Developing Cu(In,Ga)(S,Se)2 thin film photoelectrochemical solar cells via spray pyrolysis method

Hydrogen energy from photoelectrochemical (PEC) solar cells is considered as a promising candidate due to the increasing global energy demand and limited availability of conventional energy sources based on fossil fuels. In this promising energy field, especially Cu (In,Ga) (S,Se)2 thin films possessing many advantages, are developed by spray pyrolysis method which is one of the most economical production techniques. In this context, after giving a brief introduction for the photoelectrochemical solar cells in the first part of the thesis, the second part gives the information about the thin films prepared in different stoichiometries and resultingly the optimum composition for Cu (In,Ga) (S,Se)2 thin film has been detected. The third chapter contains multi-layered junction composed of Cu (In,Ga) (S,Se)2 and In2S3 thin films which were fabricated via spray pyrolysis and their photoelectrochemical performance measurements. In the fourth chapter, PEC performance measurements have been investigated by altering the configuration of the thin film. Additionally, the precursor sources of the Cu (In,Ga)S2 thin film have been altered in the spray pyrolysis process to detect the optimum conditions for better PEC performance in the fifth part. In order to produce a sufficient electron transport layer, ZnO thin films in various composition have been prepared. In addition to that, 3D ZnO nanostructure thin film has been prepared to be an alternative to spray pyrolysis of ZnO in chapter seven. Later on, Sn-ZnO (TZO) nanocomposite structure has been formed via spray pyrolysis method on zinc oxide structures produced by chemical bath deposition method. The optimal Cu(In,Ga)S2 composition obtained in previous sections combined with In2S3 thin film layers have been followingly applied on the prepared substrates. As a result of the performance measurements, an enhancement of quantum yield efficiency as 47.2 %, applied bias photocurrent efficiency as 4.17 % have been obtained. This enhancement in efficiency has been supported by morphological and optical characterization methods.