The fabrication of perovskite/Si tandem solar cells often encounters the challenge of selecting a suitable sputtering buffer layer (SBL) to prevent damage during the transparent electrode deposition. In their recent work, researchers from China's Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU), Chinese Academy of Sciences and Ningbo New Materials Testing and Evaluation Center Co. developed a perovskite-silicon tandem solar cell that uses an indium oxide sputtering buffer layer to protect the perovskite absorber and the electron transport layer from damages that might occur during the electrode deposition process. The new layer not only granted this protection but also showed strong optical and electrical properties.
The team introduced the indium oxide (In2O3) buffer layer via e-beam deposition to fabricate semi-transparent perovskite solar cells. The optical transmittance and electrical conductivity of In2O3 highly depend on the deposition rate. High deposition rate results in high ratio of metallic indium in the film, which causes severe parasitic absorption. A 20 nm-thick In2O3 film deposited at lower rate demonstrated high conductivity, transmittance and robust protection during sputtering.
A 1.68 eV semi-transparent perovskite solar cell incorporating this In2O3 buffer layer exhibited a champion PCE of 20.20%, demonstrating the excellent optoelectronic and protective properties of In2O3.
When combined with a Si subcell, the 4-terminal TSC obtained a remarkable PCE of 30.04%.
The unencapsulated semi-transparent perovskite solar cell maintained 80% of initial PCE after 423 h of continuous light soaking in N2.
This work presents a facile and instrumental transparent SBL strategy for perovskite/Si tandem solar cells.
