High Efficiency Hybride Tandem Solar Cells
Crystalline silicon modules will, sooner or later, reach their single-junction practical limits as the ultimate improvements are increasingly costly. Addition of a thin film component cell through a 4-terminal tandem concept can overcome this barrier.
The objective is to improve the efficiency of crystalline silicon (c-Si) cells to ~30% by developing a multibandgap hybrid tandem concept with a thin film solar cell with large band gap in front of the c-Si cell. Materials and cell components will be adapted to a 4-terminal tandem device. A single junction c-Si cell has a Shockley-Queisser limit of 29%.
Within this project we investigate tandem structures of a wide-bandgap (WBG) thin-film top cell and a high efficiency back-contacted silicon bottom cell (either Interdigitated Back Contact (IBC) or Metal Wrap Through (MWT)), and integrated in a module (with 4 terminals). For the top cell we optimize several high-quality WBG cells, in particular a-SiO:H, chalcopyrite, and perovskite cells (ECN, TNO, University of Valencia). For contacting and reduction of parasitic absorption TCO’s with ultrahigh transmission, one broadband and one specifically for IR transmission will be developed (TNO, TU/e, Smit Ovens, SoLayTec). We will use monolithic series connection with small dead area and packaging materials with optically transparent properties (ECN, Tempress, Eurotron) and exploit light management using antireflection layers and internal micro-textures (ECN, TNO). Module designs will be made (Eurotron, Tempress, ECN) and the IP position for the NL industries will be strenghtened.
We will deliver hybrid tandem cells with an efficiency >25% and lay out the path to cell and module efficiencies beyond 30%. We demonstrate a prototype 4-T multibandgap tandem cell using full-size 156 x 156 mm wafers including series connection of the wide band-gap thin film cell.