Fig. 3

Optical characterization of tandem solar cells with nanoholes array. a Absorption spectra versus filling ratios at fixed P = 400 nm and h = 600 nm. b Absorption spectra versus filling ratios at fixed P = 500 nm and h = 600 nm. c Photocurrent density versus filling ratios at different periods. d Increasing photocurrent density versus the filling ratios under the condition of P = 500 nm