The effect of dopant concentration on properties of transparent conducting Al-doped ZnO thin films for efficient Cu2ZnSnS4 thin-film solar cells prepared by electrodeposition method

Abstract

Al-doped ZnO (AZO) thin films were potentiostatically deposited on indium tin oxide substrates. The influence of the doping level of the ZnO:Al films was investigated. The results of the X-ray diffraction and scanning electron microscopy analysis revealed that the structural properties of the AZO films were found polycrystalline with a hexagonal wurtzite-type structure along the (002) plane. The grain size of the AZO films was observed as approximately 3 lm in the film doping with 4 mol% ZnO:Al concentration. The thin films also exhibited an optical transmittance as high as 90 % in the wavelength range of 100-1,000 nm. The optical band gap increased from 3.33 to 3.45 eV. Based on the Hall studies, the lowest resistivity (4.78 9 10-3 X cm) was observed in the film doping with 3 mol% ZnO:Al concentration. The sheet resistant, carrier concentration and Hall mobility values were found as 10.78 X/ square, 9.03 9 10 18 cm-3 and 22.01 cm 2 /v s, respectively, which showed improvements in the properties of AZO thin films. The ZnO:Al thin films were used as a buffer layer in thin-film solar cells with the structure of soda-lime glass/Mo/Cu 2 ZnSnS 4 /ZnS/ ZnO/Al grid. The best solar cell efficiency was 2.3 % with V OC of 0.430 V, J SC of 8.24 mA cm-2 and FF of 68.1 %.

Effect of Al-Doping on the Optical Properties of ZnO Thin Film Prepared by Thermal Evaporation Technique

“…This result may be due to the reduction of the voids in the sample and the improvement of the homogeneous structure with uniformly distributed particles, thereby increasing the optical scattering. The increased optical transmittance is related to the crystallinity of the film, which is in accordance with the findings of workers Kim H. et al [18] and E. M. Mkawi et al [17]. The absorption coefficient (α) of ZnO:Al thin films system has calculated by using equation [19]:…”

“…Many researches of Al-doped ZnO thin films are presented. The Al-doped ZnO thin film showed high transmittance and crystallinity [17]. In this work, it study the optical properties of ZnO:Al thin films prepared by thermal evaporation method.…”

Doped Zinc Oxide Nanostructures for Photovoltaic Solar Cells Application

“…Therefore, 3% Cu concentration could be the optimum concentration of Cu in ZnO to provide the best crystalline quality film in CZO thin films. This observation slightly defers from an earlier report of Babikier et al and Mkawi et al [22,25] even though they used different concentrations of Cu.…”

An investigation of effects of bath temperature on CdO films prepared by electrodeposition

“…5. The relationship between the absorption coefficient and photon energy for direct allowable transition can be denoted as (Vishakha et al 2013;Mkawi et al 2015);…”