Silicon heterojunction solar cells achieving 26.6% efficiency on commercial-size p-type silicon wafer

Summary

Heterojunction formed at the amorphous/crystalline silicon (a-Si:H/c-Si) interface exhibits distinctive electronic characteristics for application in silicon heterojunction (SHJ) solar cells. The incorporation of an ultrathin intrinsic a-Si:H passivation layer enables very high open-circuit voltage (V_oc) of 750 mV. Furthermore, the n- or p-type doped a-Si:H contact layers can undergo crystallization into mixed phases, mitigating parasitic absorption while simultaneously enhancing carrier selectivity and collection efficiency. In this study, we have employed phosphorus diffusion gettering pretreatment on the wafers and pioneered the development of carrier-selective contacts using nanocrystalline silicon (nc-Si:H) to substantially enhance the efficiency of p-type SHJ solar cells to an unprecedented 26.56%, thus establishing a new performance benchmark for p-type silicon solar cells. The process development and optoelectronic property improvement of the devices are introduced in detail. Power loss analysis is performed to pinpoint the path for future development of the p-type SHJ solar cell technology.