Effect of Intrinsic Amorphous Silicon Film Thickness on the Performance of Heterojunction Solar Cell with Copper Electrode

The excellent passivation of intrinsic amorphous silicon (i-a-Si:H) on crystalline silicon substrates is key to achieving high conversion efficiency in heterojunction with intrinsic thin-layer (HJT) solar cells, and the thickness of the intrinsic amorphous silicon film is a critical factor influencing its passivation quality. This study systematically investigates the effect of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{i - a - S i: H}$</tex> thickness on the electrical performance of HJT solar cells. The results show that reducing the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{i}-\mathrm{a}-\text{Si}: \mathrm{H}$</tex> thickness effectively decreases parasitic optical absorption, thereby improving the short-circuit current (Jsc) and reducing series resistance (Rs). However, excessively thin films degrade the passivation effect on the silicon wafer surface, leading to reduced open-circuit voltage (Voc) and pseudo fill factor (PFF). Through optimization, a balance between passivation quality, parasitic absorption loss, and series resistance is achieved at an i-a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Si}: \mathrm{H}$</tex> thickness of 7 nm. This results in the highest cell conversion efficiency, with an average relative efficiency improvement of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{2. 0 \%}$</tex> for the optimized batch.