Numerical Simulation of Copper Indium Gallium Diselenide Solar Cells Using One Dimensional SCAPS Software

The effect of multivalent defect density, thickness of absorber and buffer layer thickness on the performance of CIGS solar cells were investigated systematically. The study was carried out using Solar Cells Capacitance Simulator (SCAPS) code, which is capable of solving the basic semiconductor equations. Employing numerical modelling, a solar cell with the structure Al|ZnO : Al|In2S3|CIGS|Pt was simulated and in it, a double acceptor defect (-2/-1/0) with a density of 1014 cm-3 was set in the absorber in the first instance. This initial device gave a power conversion efficiency (PCE) of 25.85 %, short circuit current density (Jsc) of 37.9576 mAcm-2, Photovoltage (Voc) of 0.7992 V and fill factor (FF) of 85.22 %. When the density of multivalent defect (-2/-1/0) was varied between 1010 cm-3 and 1017 cm-3 the solar cells performance dropped from 26.81 % to 16.87 %. The champion device was with multivalent defect of 1010 cm-3 which shows an enhancement of 3.71 % from the pristine device. On varying the CIGS layer thickness from 0.4 um to 3.6 um, an increase in PCE was observed from 0.4 um to 1.2 um then the PCE began to decrease beyond a thickness of 1.2 um. The best PCE was recorded with thickness of 1.2 um which gave Jsc of 37.7506 mAcm-2, Voc of 0.8059 V, FF of 85.2655 %. On varying the In2S3 (buffer) layer thickness from 0.01 um to 0.08 um, we observed that there was no significant change in photovoltaic parameters of the solar cells as buffer layer thickness increased.

Micro-Tubular Solid Oxide Fuel Cell Polarization and Impedance Variation With Thin Porous Samarium-Doped Ceria and Gadolinium-Doped Ceria Buffer Layer Thickness

Porous buffer layers for anode-supported solid oxide fuel cells (SOFCs) have been investigated for many years with different thicknesses of the buffer layer in each study. In this work, micro-tubular SOFCs having samarium-doped ceria (SDC) and gadolinium-doped ceria (GDC) buffer layers are compared using the current–voltage technique, electrochemical impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The thickness of the porous SDC and GDC buffer layer is investigated systematically with the thickness varying between 0.3 and 2.0 μm. The power density varies between 212 and 1004 mW/cm2 for samples having different SDC buffer layer thickness. Comparable changes occur for the SOFCs with a GDC buffer layer, but less variation in polarization losses resulted. Variation in electrochemical performance varies due to changes in ohmic resistance, cathode activation polarization, and interfacial reactions between the cathode and electrolyte materials.