SCAPS-1D Modeling of CdTe Solar Cells Featuring a Dual-Layer FTO/ITO Transparent Conductive Electrode

The numerical modeling of thin-film solar cells has become an essential tool for accelerating device development and reducing the experimental cost. Although CdTe technology has exceeded the 22% certified efficiency, further gains are curtailed by front-contact optical losses and electronic defects in the absorber. To address these limitations, we used SCAPS 1D to optimize a CdTe stack employing a bilayer transparent conductor (FTO/ITO), a ZnO electron transport layer (ETL), a CdTe absorber layer, and a Cu<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O hole transport layer (HTL). With a bulk trap density of 1 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup>, the simulation predicts a power conversion efficiency (PCE) of 25. 20%, with a fill factor (FF) of 84. 69%, an open circuit voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</inf>) of 1.21 V and a short circuit current density (J<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</inf>) of 24.50 mA/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. Thickness sweeps indicate that CdTe films thicker than 650 nm add negligible current (< 0.1% PCE gain) but increase material usage.