Characterization of Transition Metal Oxide/Silicon Heterojunctions for Solar Cell Applications

Luis Gerling, Somnath Mahato, Cristobal Voz, Ramon Alcubilla, Joaquim Puigdollers
2015 Applied Sciences  
During the last decade, transition metal oxides have been actively investigated as hole-and electron-selective materials in organic electronics due to their low-cost processing. In this study, four transition metal oxides (V2O5, MoO3, WO3, and ReO3) with high work functions (>5 eV) were thermally evaporated as front p-type contacts in planar n-type crystalline silicon heterojunction solar cells. The concentration of oxygen vacancies in MoO3−x was found to be dependent on film thickness and
more » ... thickness and redox conditions, as determined by X-ray Photoelectron Spectroscopy. Transfer length method measurements of oxide films deposited on glass yielded high sheet resistances (~10 9 Ω/sq), although lower values (~10 4 Ω/sq) were measured for oxides deposited on silicon, indicating the presence of an inversion (hole rich) layer. Of the four oxide/silicon solar cells, ReO3 was found to be unstable upon air exposure, while V2O5 achieved the highest open-circuit voltage (593 mV) and conversion efficiency (12.7%), followed by MoO3 (581 mV, 12.6%) and WO3 (570 mV, 11.8%). A short-circuit current gain of ~0.5 mA/cm 2 was obtained when compared to a reference amorphous silicon contact, as expected from a wider energy bandgap. Overall, these results support the viability of a simplified solar cell design, processed at low temperature and without dopants. OPEN ACCESS Appl. Sci. 2015, 5 696
doi:10.3390/app5040695 fatcat:dn6f6nkapfenhgi4xazm4jqyou