Limit of absorption enhancement in solar cells with guided modes

Providing green energy for human consumption has become a main goal of industry and research in recent decades. Photovoltaic technology is a main candidate for this aim but it requires price reduction and efficiency increase to enable large scale commercialization. To comply with the cost effectiveness, the cells can be made very thin to reduce material consumption and materials with well-established technology e.g. silicon are preferred. However, at long wavelengths light absorption in in silicon based materials becomes weak due to their indirect band gap. Therefore, methods are required to boost light absorption in the cell or literally “trap light” inside the cell.