A downshifting Eu3+ doped glass embedded with concave pyramid microstructure to improve the efficiency of silicon solar cell

Abstract

The average photoelectric conversion efficiency (PCE) of a bare mono crystalline silicon solar cell is 14.71% ± 0.03% under AM1.5. It decreases to 14.20% ± 0.005% when covering an un-doped flat glass on the solar cell, and it goes down to 14.10% ± 0.005% by using a 5 wt% Eu3+ doped glass. The absorptions of the Eu3+ doped CPM glass one-to-one match the excitation spectra at 362, 381, 393, 400, 413 and 464 nm, which are related to the transitions of 7F0→(5D4, 5G2, 5L6, 5D3), 7F1→5D3, and 7F0→5D2, respectively. In addition, a concave pyramid microstructure (CPM) is embedded in the glass surface to increase light transmittance. The average PCE increases to 14.61% ± 0.07% when a 5 wt% Eu3+ doped CPM glass covers on the silicon solar cell. Compared with the un-doped flat glass, a net increase of the PCE is 0.41%, where the 0.16% increment of PCE is from the lighting trapping of the CPM structure, and the downshifting of near ultraviolet (NUV) light by Eu3+ ion donates the other 0.25% increment. It confirms that the as-prepared Eu3+ doped CPM glass has a good downshifting and antireflection function.