| Spin Coating Speed (rpm) | Thickness (nm) | Energy Band Gap (eV) |
| 1000 | 127.40 | 3.31 |
| 2000 | 109.10 | 3.40 |
| 3000 | 97.60 | 3.30 |
| 4000 | 91.30 | 3.29 |
| 5000 | 84.70 | 3.23 |
| 6000 | 81.50 | 3.25 |