Bilayer MoO_X/CrO_X Passivating Contact Targeting Highly Stable Silicon Heterojunction Solar Cells

Abstract

Molybdenum oxide (MoO X , X < 3) has been successfully demonstrated as an efficient passivating hole-selective contact in crystalline Si (c-Si) heterojunction solar cells because of its large bandgap (∼3.2 eV) and work function (∼6.9 eV). However, the severe performance degradation coming from the instability of the MoO X and its interfaces has not been well addressed. In this work, we started with a c-Si(p)/MoO X heterojunction solar cell that yielded a power conversion efficiency (PCE) of 15.86%, in which the MoO X film was synthesized by industry-compatible atomic layer deposition (ALD). The initial PCE dropped to 10.20% after 2 days because of severe migration of O and Ag at the MoO X /Ag interface. We solved this by the insertion of a CrO X layer between the MoO X layer and the Ag electrode. The solar cell was found to be stable for more than 8 months in air because of the suppression of interface degradation. Our work demonstrates an effective way of improving the stability of silicon solar cells with transition metal oxide carrier selective contacts.

Stable MoOX‐Based Heterocontacts for p‐Type Crystalline Silicon Solar Cells Achieving 20% Efficiency

“…A longer UV/O 3 treatment results in a decrease in PCE, which is primarily due to the depression of the fill factor (FF). Since longer UV/O 3 treatment leads to a higer X value in the SiO X , [ 36 ] the trap‐assisted tunneling [ 37 ] becomes difficult. This could be the reason for the FF drop.…”

Post-annealing Effect on Optical and Electronic Properties of Thermally Evaporated MoOX Thin Films as Hole-Selective Contacts for p-Si Solar Cells

“…MoO X films can be deposited by atomic layer deposition [ 30 – 34 ], reactive sputtering [ 12 ], pulsed laser deposition [ 35 ], thermal evaporation [ 24 , 36 ] and spin coating [ 37 ]. In most of the solar cell researches based on Si/MoO X contact, MoO X films are prepared by thermal evaporation at room temperature [ 8 ].…”

Post-Annealing Effect on Optical and Electronic Properties of Thermally Evaporated MoOX Thin Films as Hole-Selective Contacts for p-Si Solar Cells

“…Overall, the performance of the p-Si/MoO X heterojunction solar cell is affected by the passivation quality, work function and band-to-band tunneling [31] properties of the hole-selective MoO X lm. The passivation performance of the present structure is still poor, leading to relatively lower V OC .…”

“…MoO X lms can be deposited by atomic layer deposition [28][29][30][31], reactive sputtering [10], pulsed laser deposition [32], thermal evaporation [22,33] and spin coating [34], etc. In most of the solar cell researches based on Si/MoO X contact, MoO X lms are prepared by thermal evaporation at room temperature [6].…”