Performance improvement of an ultra-thin amorphous silicon solar cell using multilayers chirped diffraction back gratings

In this paper, a systematic design of a novel back reflector using chirped grating structures is investigated for thin-film amorphous silicon (a-Si) solar cells. At first, a cell with an optimum ITO antireflecting layer is simulated and a photocurrent of 17.67 mA cm(-2) is obtained. Then a conventional grating from SiO2 is evaluated and the maximum photocurrent of 18.97 mA cm(-2) is calculated. Then a thin-film solar cell based on the chirped back grating is designed and the photocurrent is increased to 19.30 mA cm(-2). Also, their integrated optical absorption is compared for better understanding. To give a numerical comparison of the cells with a different number of chirped grating layers, a short circuit current for different numbers of grating layers is analyzed. It is shown that maximum current density is obtained for 5 layers grating with the chirped coefficient length of near 20 nm. It is believed that chirped back grating can be used to design higher performance thin film a-Si solar cells and the results are helpful for photovoltaic applications.

Automated summary

In this paper, a systematic design of a novel back reflector using chirped grating structures for thin-film amorphous silicon solar cells is investigated. The results show that the use of chirped back grating can increase the photocurrent and improve the optical absorption, which is helpful in designing higher performance thin film solar cells.