Transparent-conductive-oxide-free front contacts for high-efficiency silicon heterojunction solar cells

Summary In order to compensate the insufficient conductance of heterojunction thin films, transparent conductive oxides (TCO) have been used for decades in both sides contacted crystalline silicon (SHJ) solar cells provide lateral conduction carrier collection. this work, we substitute TCO layers by utilizing c-Si absorber, thereby enabling a TCO-free design SHJ achieving low series resistivity 0.32 Ωcm2 and good fill factor 80.7% with conventional finger pitch 1.8 mm. Achieving high efficiencies requires suppressing deterioration passivation quality induced direct metal-to-a-Si:H contacts. We show that an ozone treatment at a-Si:H/metal interface suppresses metal diffusion into a-Si:H layer improves without increasing contact resistivity. front contacts achieve >22%.