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The Stability Effect of Atomic Layer Deposition (ALD) of Al2O3 on CH3NH3PbI3 Perovskite Solar Cell Fabricated by Vapor Deposition

The perovskite solar cells (PSCs) with Al2O3 passivation layer were fabricated and characterized. The PSC have some advantages of easier and cheaper fabrication process than that of conventional Si solar cells, III-V compound semiconductor solar cells, and organic solar cells. The perovskite light harvester, CH3NH3PbI3, was deposited by vapor deposition on [compact TiO2 / F-doped tin oxide (FTO) / glass]. The advantage of vapor deposition over solution process is expected to be able to offer the thin film with smoother surface over larger area. Then, Al2O3 passivation layer was deposited by atomic layer deposition (ALD) on the CH3NH3PbI3 light harvester. Al2O3 passivation layer was expected to prevent the CH3NH3PbI3 light harvester from oxidation and improve the solar cell efficiency, and ALD has been one of the most effective methods to deposit Al2O3 thin film for last 25 years. The atomic layer deposited Al2O3 layer thickness was optimized from the solar cell characterization. The optimized power conversion efficiency (PCE) and Al2O3 thickness were ~8.0 % and ~10.0 nm, respectively.