Photovoltaic properties of the sealed solar cells (the active area is 4 mm × 4 mm) were measured by using a Keithley 2400 SourceMeter under illumination of simulated sunlight (1000 W m−2) pro-vided by a Peccell Technologies, Inc. solar simulator with an AM1.5G filter. EQE plotted as a function of excitation wavelength wasrecorded on a Keithley 2400