New material boosts bifacial solar cell efficiency from the back side
Researchers have identified a titanium-doped coating that improves light capture in advanced solar cells, delivering 3 milliamps per square centimeter more current during rear illumination. The finding could help manufacturers increase solar panel output without redesigning production lines, addressing growing demand for high-efficiency bifacial systems in utility-scale deployments.
Originaltitel: Titanium-Doped In<sub>2</sub>O<sub>3</sub>: A High-Mobility, Thermally Stable Back Contact for Bifacial Chalcopyrite Solar Cells
<p>This study evaluates In<sub>2</sub>O<sub>3</sub>:Ti as a transparent back contact (TBC) material in bifacial (Ag,Cu)(In,Ga)Se<sub>2</sub> (ACIGS) solar cells with a band gap of 1.1 eV and compares it to commonly used In<sub>2</sub>O<sub>3</sub>:Sn. Both TBC layers were processed with a sheet resistance ≤10 Ω/sq, as required in a monolithically series-connected ACIGS module. In contrast to several other high-mobility TBCs previously tested in ACIGS solar cells, In<sub>2</sub>O<sub>3</sub>:Ti retains its exceptionally high mobility (>100 cm<sup>2</sup>/Vs), low resistivity (2.4·10<sup>-4</sup> Ωcm), and minimal near-infrared absorption (<5% at ACIGS bandgap) after high-temperature absorber deposition. As a result, an up to 3 mA/cm<sup>2</sup> higher short-circuit current density is measured under rear illumination for cells with an In<sub>2</sub>O<sub>3</sub>:Ti back contact as compared with devices using highly doped In<sub>2</sub>O<sub>3</sub>:Sn. The best cell reaches an efficiency of 10.2% at rear illumination with a bifaciality factor of 68%. At front illumination, the cell performance is on the same level for both TBCs.</p>