Bilayer\nSnO₂ as Electron Transport Layer\nfor Highly Efficient Perovskite Solar Cells

Abstract

Tin oxide (SnO₂) has been reported as a promising electron\ntransport layer (ETL) for planar heterojunction perovskite solar cells\n(PSCs). This work reports a low temperature solution-processed bilayer\nSnO₂ as an efficient ETL in gas-quenched planar-heterojunction\nmethylammonium lead iodide (MAPbI₃) perovskite solar cells.\nSnO₂ nanoparticles were employed to fill the pin-holes\nof sol–gel SnO₂ layer and form a smooth and compact\nbilayer structure. The PCE of bilayer devices has increased by 30%\ncompared with sol–gel reference device and the <i>J</i>_sc, <i>V</i>_oc, and FF has been improved\nsimultaneously. The superior performance of bilayer SnO₂ is attributed to the reduced current leakage, enhanced electron\nextraction characteristics, and mitigated the trap-assisted interfacial\nrecombination via X-ray photoelectron spectroscopy (XPS), electrochemical\nimpedance spectroscopy (EIS), and space-charge limited current–voltage\n(SCLC) analysis.