Improved hetero-interface passivation by microcrystalline silicon oxide emitter in silicon heterojunction solar cells

In this paper, we prepared silicon heterojunction (SHJ) solar cells with the structure of p-c-Si/i-a-SiOx:H/n-μc-SiOx:H (a-SiOx:H, oxygen rich amorphous silicon oxide; μc-SiOx:H, microcrystalline silicon oxide) by plasma-enhanced chemical vapor deposition method. The influence of the n-μc-SiOx:H emitter thickness on the heterointerface passivation in SHJ solar cells was investigated. With increasing thickness, the crystallinity of the emitter as well as its dark conductivity increases. Meanwhile, the effective minority carrier lifetime (τeff) of the SHJ solar cell precursors at low injection level shows a pronounced increase trend, implying that an improved field effect passivation is introduced as the emitter is deposited. And, an increased τeff is also observed at entire injection level due to the interfacial chemical passivation improved by the hydrogen diffusion along with the emitter deposition. Based on the analysis on the external quantum efficiency of the SHJ solar cells, it can be expected that the high efficient SHJ solar cells could be obtained by improving the heterointerface passivation and optimizing the emitter deposition process.