Thickness (nm)

300

500

600

ITO

FTO

ITO

FTO

ITO

FTO

E_g (eV)

Before annealing

2.74

2.62

2.47

2.51

2.35

2.01

Annealing at 300˚C

2.66

2.8

2.62

2.75

2.04

2.50

Annealing at 400˚C

2.65

2.64

2.63

2.61

2.56

2.25