Photocurrent increase in amorphous Si solar cells by increased reflectivity of LiF/Al electrodes

Thin layers of lithium fluoride (LiF), together with aluminum, can be used as rear electrodes in high-efficiency amorphous silicon (a-Si:H) solar cells on rough substrates, as recently demonstrated by Fang et al. (IEEE Transactions on Electron Devices 58(9)(2011) 3048–3052). We employ numerical modeling to evaluate the optical losses and charge generation profiles in these thin film solar cells. We find that the increase in rear electrode reflectivity by inserting LiF, leading to increased photocurrent, is the dominant factor in device performance improvement, accounting for 7% gain in photocurrent. The simulations are in good agreement with measurements of pin a-Si:H solar cells with varied rear electrodes.

► We investigate the benefit of lithium fluoride/aluminum back reflectors.
► We simulate the spectral response of amorphous silicon solar cells.
► Lithium fluoride increases the reflectivity of the rear aluminum electrode.
► The photocurrent of amorphous silicon solar cells may be increased by 7%.