Figure 2 EQE (a) and integrated current Jisc (b) of the SCH solar cells with ICO layer of different thickness.
The EQE and integration short-circuit current density (Jisc) for the SCH solar cells with back ICO films of varying thickness are depicted in Fig. 2 (a) and (b), respectively. The EQE curves almost overlap in the short wavelength range due to the same front structure. However, the quantum efficiency of long wavelength increases first and then decreases with increasing of the back ICO thickness. The back ICO thickness corresponding to the highest EQE is about 110 nm and the corresponding Jisc is 39.68 mA/cm2. As a comparison, Jisc for the SCH solar cell without back ICO is 38.51 mA/cm2. The significant improvements in long wavelength response and Jisc by adding the back ICO layer with a suitable thickness of 110 nm indicate that the ICO/Ag combination functions well as a back reflector.