Synthesis and characterization of polyaniline as plugging pinholes in CdS/CdTe.

The formation of pinholes on CdS/CdTe thin film solar cell happen due to many reasons. As a result, the pinholes lead to short circuit and eventually will degrade the performance of solar cell. This study was aimed to achieved three objectives which are to synthesis and deposit PANI thin film by varying the pH and aniline concentration, to characterize the optical, structural and morphology properties of PANI layer as plugging pinholes and to investigate the performance of PANI layer as plugging pinhole on CdS/CdTe solar cell. All the samples had been labeled as A (PANI with 0.10 M concentration of aniline and pH of acid 2.50), B (PANI with 0.25 M concentration of aniline and pH of acid 2.50), C (PANI with 0.50 M concentration of aniline and pH of acid 3.40) and D (PANI with 0.50 M concentration of aniline and pH of acid 2.50). PANI thin films had been successfully synthesized and deposited by using electrodeposition technique. From optical characterization, the band gap of PANI layer had been determined to be 3.90 eV for sample A, 4.70 eV for sample B, 3.80 eV for sample C and 3.86 eV for sample D which were higher than the whole thin film device. XRD result revealed that all the deposited PANI layers pattern are amorphous. Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. SEM results show that the most homogenous layer is A, with 0.10 M concentration of aniline, pH 2.50. This layer show cementing effect in covering all the substrate with a very thin layer of PANI and suggested that this layer is the most suitable to be chosen as plugging pinholes on solar cell device. Finally, the test on efficiency of solar cell device with layer of PANI show the best increment of efficiency goes to layer of 0.10 M of PANI with the efficiency of 3.1% as compared to uncoated solar cell which is only 1.7%. Keywords: Polyaniline, aniline monomer, acidic pH, conducting polymer, emeraldine base, oxidation state.