Hot wire Oxidation–Sublimation derived work function tunable WOx thin films for building hole-selective contacts

The replacement of doped amorphous silicon (a-Si) with transparent passivation materials is an alternative approach to promote the efficiency of silicon heterojunction (SHJ) solar cells. Transition metal oxide, especially tungsten oxide (WOx) is attractive for adhibition in SHJ solar cells as the substitute, due to the wide-bandgap, adjustable work functions, and relatively high stability. Here we introduced a hot wire oxidation-sublimation deposition (HWOSD) for preparation of WOx films, realizing precise modulation of their work function ranging from 4.9 to 5.4 eV. Notably, no loss of passivation quality relevant to the pre-deposited passivating layer of hydrogenated amorphous silicon (a-Si:H) was betrayed when completed the coating of WOx films. The hole-selective contacts of a-Si:H/WOx stack are utilized in SHJ solar cells, delivering a power conversion efficiency of 21.0 %.