When ) -( )) (Figure (f)). Comparing before and after contact, the VB and CB offsets decrease when SnO2 and TiO2 in contact. These results could be due to the transfer of electrons from TiO2 (band structure goes down) to SnO2 (band structure goes up). The next section will explain this transfer. Valence band edge spectra of TiO2 (c) and SnO2 (d). Band alignment of materials before contact (e) and after contact (f). These results were reproduced and rearranged from ref. .