Fabrication and characterization of transition metals (Mn and Co)-doped cds-based photovoltaic cells

In this study, CdS thin films were produced via chemical bath deposition method, individually doped with Mn (0.5%, 1%, 2%) and Co (1%, 3%, 5%, 7%), on indium tin oxide (ITO) coated glass substrates. Additionally, the desired device configuration was achieved by coating N719, P3HT:PCBM, and PEDOT:PSS organic layers, respectively, using spin coating method. Comprehensive XRD, SEM, EDS, transmittance, absorbance, PL analyses were conducted on both Mn and Co-doped CdS thin films and the fabricated solar cells. Furthermore, J-V tests were performed on the fabricated devices. XRD analysis revealed that the produced CdS thin films grew in a cubic structure. Addition of Mn atoms into CdS structure was determined to deteriorate crystal quality based on dislocation density and micro-strain results. Mn doping led to a positive effect on transparency of CdS films, particularly achieving over 90% transmittance in the wavelength range of 500-650 nm for CdS sample with 2% Mn addition. Mn doping was found to increase forbidden energy band gap of CdS, causing a blue-shift in absorption edge. J-V measurements of the fabricated solar cells indicated that Mn doping improved the efficiency of CdS based hybrid solar cells. Highest power conversion efficiency was achieved with a 2% Mn-doped CdS solar cell (0.202%). On the other hand, Co doping led to a change in the unit cell volume and increase in crystalline size of CdS. Additionally, a reduction in grain size of CdS thin films was observed with Co doping. Co doping was found to enhance optical transparency of CdS films and alter the forbidden energy band gap. Photoluminescence results suggested that Co doping caused additional defect states in CdS films. Furthermore, Co doping positively influenced the efficiency of CdS-based hybrid solar cells, with highest efficiency obtained from solar cells with 1% Co doping (0.488%).