Optical and Electrical Characterization of Sns – Sno2: Sb P-N Junction for Solar Cell Applications
Ombagi, Okinyi Dennis
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For sustainability of future civilization, development of alternative clean energy technologies to replace fossil fuels has become one of the most crucial and challenging problems of the last few decades. Thin film solar cells is one of the major photovoltaic technologies that is promising for renewable energy conversion. The PV cells currently in use today are silicon based, though other cells have been fabricated using other semiconductors. Recent research is focused on fabrication of solar cells with high conversion efficiency. In this research, SnS and SnO2:Sb films were optimized for photovoltaic applications. The SnO2:Sb films were deposited by Spray pyrolysis technique and SnS films were deposited by Chemical Bath Technique. Solid spec 3700 DUV- VIS double beam spectrophotometer was used to study their optical properties. The four-point probe connected to Keithley 2400 source meter was used in studying the electrical properties of film samples obtained. The prepared SnS thin film samples had transmittance of between 1-30% and reflectance recorded was between 9-45%. The energy band gap of the absorber layer films obtained was ranging from 1.27 - 1.68 eV. SnS thin films obtained indicated resistivity decreasing from 407.8-33.5 Ωcm as the concentration of SnCl2 increased from 0.05M – 0.20M. The window layer (SnO2:Sb) had a transmittance which was ranging between 32-88 % and reflectance that ranged between 7-39 % within the visible region. Energy band gap for SnO2:Sb ranged between 3.52-3.93 eV for Sb doping of 0-5 wt. %. Resistivity of SnO2 and SnO2:Sb ranged between 2.97 – 14.71 Ωcm. The thin films that were optimized were used in fabrication of SnS - SnO2:Sb P – N Junction. The fabricated PV solar cell parameters were obtained and they include; Isc= 0.0905 mA, I max= 0.06934 mA, Voc=435.1 mV, Vmax=342.6 mV, FF=0.60 mA, and 𝜂= 0.012 %. Therefore SnS and SnO2: Sb thin films are suitable for making solar cells.